I've also been reading The War Altar and its observations of the past few month's tourneys in Ireland, and the fact that TWC were popular among the Wolf players but not one of my staples.
There's a couple of factors that I think count against regular TWC but they're easily summarised here:
1. Weapon Skill
Simply put: WS 4 is not fantastic. Its only average. Despite having a lot of attacks TWC will only typically hit their opponents in combat on a 4+. That's not great for something that's 50+ pts per model. As regular IC's can't join them and without the ability to get re-rolls barring Wolf Claws (the solitary special weapon in the squad? No thanks, I'd prefer S10) they've got no way to boost this if they're built to take on all-comers as those squads will usually have a Hammer/Fist to allow them to crack anything.
Solitary TWC with Wolf Claws are an exception to this but they've got a dedicated anti-infantry role where they don't expose themselves as much as larger TWC units, meaning they are less likely to get jumped by the more-dangerous enemy combat types.
|You tell 'em Starscream.|
E.g. You pop the unit's ride and they take a Pinning test. If the vehicle explodes and kills 25% it is also a Morale test. That's 2 right there in one turn and you haven't even take a shot at them yet.
|TWC footprints: Not even Jesus can save you now.|
I will gladly throw 3 Rhino chassis at them to drive them back and potentially force them to run away 3D6" on top of the push-back move my tank creates. Its usually not worth throwing your vehicles at smaller sized units btw - just shoot them to death or take them out with your own combat monsters. If they have been forced to flee their footprint comes back to dick them again: it'll be easier to park a unit within 6" of them preventing them from rallying and running another 3D6" toward their own board edge.
You can boost this with addition of a character but that obviously uses up even more points which can weaken your support units. Remember: you'll need plenty of Grey Hunters to claim objectives up 2 stories of a building and Long Fangs to crack open transports.
So they've got a MEQ save. That's fine, a 3+ to small arms fire and a 4+ to low AP stuff assuming cover (remember their footprint is double-edged: bad for tank-shocking but good for getting cover) while you get a 3+ from any Storm Shields you equip the unit with. You also get the ability to engage in wound-allocation shenanigans by giving all your guys different gear which while not in Nob biker territory is still pretty handy to having all of your expensive guys reach the enemy relatively intact.
Their problem is that their save is only average. When exposed to torrent of fire they're in trouble: they'll take a wound 1/3 of the time which is the same as a Marine. Sure, their 2 wounds requires opponents to apply more firepower but when you consider their small unit size and the fact they will have a hard time hiding behind LOS-blocking terrain (their fecking footprints are now so prominent in this article it might be time for some dancing to cheer yourself up: woo ooh hoo ooh ooh hoo ooh ooh ooh) they will be exposed, especially when compared to other army's deathstars as they're usually tougher or riding in Transports. Hell, even your GH units in transports aren't exposed in the same way.
Granted Storm Shields can help you against low-AP stuff but then you risk having him tumble early on and exposing the unit to more damage from power weapon equivalents tearing through your armour in combat. Their speed is a factor in getting them across the board in one piece and silencing your enemy's firepower (footprint: good - multi-charging) but when you do that you risk exposing the unit, being cockblocked/tank-shocked by vehicles and further shot up as well as your enemy simply taking a turn to move up a level if terrain allows. That's assuming they're not already deployed there babysitting an objective that your TWC can't get to...
The lack of a 2+ save is a problem for them, and a big reason I prefer to take HQ's as, like the GH's Ld boost by 1 with a Wolf Guard, there is a big improvement when you move from a 3+ to a 2+ save. Missile Launchers and torrent no long scare you as they did and you don't need to rush into cover and risk rolling poorly for movement in terrain. This makes a character with a 2+ save a great buy for a unit of TWC but again it brings problems for him when the other guys in the unit fall over and he has to take Morale tests sans re-rolls. There's also the risk of losing combat when your regular guys get pasted dropping the unit's Ld and running away 3D6". A deathstar shouldn't have to have a character leading them anyway to be effective and TWC really need one to give them the boosts they need, significantly adding to their expense. That leads me nicely to...
The options open to TWC unit are limited and expensive, which you would expect from a decent combat unit but which are prohibitively high in trying to make them as survivable or as killy as Deathstars normally are. Shields being 30 points are too expensive to have more than one or two in a unit as buying 2 of them will costs you more than another warm body being added to the squad. And as we all know one of the better rules of army building is 'Boys before Toys'.
One good thing about the restriction of Special weapons in the squad is that you keep more points for grunts and other units, although this restricts the killiness of the squad and means that you have to add a character to the unit to get a 2nd weapon that ignores regular armour. Hooray - they're even more expensive.
The one caveat to this is that if you take a single TWC with Hammer and Shield or Wolf Claw and shield and use them as Killswitch suggests here. You get a unit that won't attract as much attention as larger units and is cheaper, but its nothing close to a Deathstar and is relatively easy to kill off.
Well if you're going to say something is crap then you need a comparator. In this case I'm looking at TWC HQ's. But not Canis. He's terribad: no invul save and he makes your ablative wounds/re-roll to Ld tests Troops. That don't score. Right...
Going with the same 4 criteria above (I'm limiting stuff so I can actually finish this post) your HQ's are superior.
1. HQ's on TWC have higher WS making it easier to hit enemies while its harder for them to hit back, assuming WS 4-5. You also have the option (for a bargain 10 points) to have them hit everybody on 3's making them very reliable when they get stuck in. It also makes your decision easier when you have to choose what to use re-rolls for with a Wolf Claw. Its re-rolls to hit all the time except against T5+ btw.
2. A WGBL is Ld 9, a Lord is 10. With the option to join Fenrisian Wolf units available to them you don't just get a screen of ablative wounds for shooting (be careful you don't get assaulted with lots of the Wolves still alive...) but the unit will get to re-roll any Morale test thanks to the Wolves' Wolfkin rule as long as one of them is alive. There goes the Tank-shock problem...
3. With the option of Rune Armour for 20 points as well as the wolfblob mentioned above you can seriously increase the survivability of your characters. In fact, you can make them nigh-untouchable for the first couple of turns if you buy enough Wolves, take cover and allocate all of the hits onto them leaving the HQ's unaffected. You don't have as many wounds with characters but with the improved armour save you'll suffer less not to mention being hidden in a blob means you won't suffer any.
4. Here's where the characters lose out but that's par for the course. Their options are expensive but they are far more flexible than their regular counterparts. You need something to maul infantry: you've got Frost Blades and Wolf Claws. Monsters and Deathstars a problem? Thunder Hammers and Saga of the Bear to the rescue.
Instead of running a 250+ point monster-Lord you can always spread the love and run a pair of cheap WGBL's and throw them into a Wolfblob and use them to snipe stuff by running forward and leaving the unit to assault. For the same cost as a unit of regular TWC you'll usually get a character that's more killy and tougher. Again, a caveat: instead of a lone WGBL I'd recommend that you go with a solitary TWC as they're a lot cheaper and can fulfil the same role. If you want TWC in numbers I recommend that you go balls-to-the-walls (which you should be doing with them like...anseo) and splash out on HQ's attached to Fenris Wolf units rather than regular TWC.
|This guy does deserve a special mention.|
Saying that he's still a cheaper option available to you when you want something with S10 and lots of wounds, and becomes much tougher to take out when a HQ joins him so you can take advantage of their T5 ablative wounds (4 Cyberwolves and 2 pets is quite handy) and you can give him a Necklace so he hits everyone on 3's. But again, you're looking to your characters which costs a lot of points.
The Iron Priest vs TWC question is harder to answer than the HQ vs TWC/Iron Priest one and will depend on personal preference. Regardless, you're better off going with the HQ choice over either, preferably with a few ablative Fenris Wolf wounds.
TWC are ok, TWC HQ's are much better. Buy them instead.