Thinking about a Warlock-heavy group....

[AlienChild]

I play on a PvP server. I am thinking of the following 5-man combination:

Prot Pally, Rest Shaman and 3xWarlocks (perhaps replacing Pally with DK)

How would this group compare to the traditional:

Prot Pally (or DK) + 4xShaman

For running heroics and some world PvP?

[Ualaa]

For pvp, compared to multiple shaman's, you are much more vulnerable to Fear Bombs.
Warlocks could be Felguard spec 0/41/30 perhaps, which gives you a fair bit of passive AoE and the Intercept.
You could go one warlock as Affliction, for the UA dot protection.
A lot of instant casts and you have AoE fear yourself, multiple times.
Everyone hates warlocks because of Fear and that they can suddenly have 4-5 dots on their toon.
You can give them 15 dots in that same time, which is rather sick.
Multiple succubi are possible for Seduce as well, if you set up the macro's right.
PvP wise, you'll be markedly worse in arena, but do fine in world/BG's other then the fear bombs.
Both teams have an awful lot of AoE power which is nice too.

Resto shaman synergizes very well with the Paladin and any caster DPS.
Very good mana regeneration, and if the shammy totem changes (supposed to be 3.2) go through as advertised, that will be very nice.
They all use and benefit from mana, and are all casters.
A DK will work fine as well, but a Paladin will be easier to box at close to 100% efficiency.

As far as PvE heroics/raids go, Paladin/Resto/Warlocks should be able to do most/all content.
A Paladin/4xShaman's is a simpler group, as in fewer keys to worry about, but more toons is more options and flexibility.
Warlocks are very high sustained dps, while Shaman's are higher burst. PvE advantage to the Locks I would say.
Pally can DI the Resto, Resto can Ankh and you'll have 3x Soul Stones for strong recovery options.

The paladin wants Tanking-Plate.
The shaman wants Caster-Mail.
The warlocks want Caster-Cloth.
That's less fighting over gear then 4x shamies plus a pally, but still 3x one gear type.

If you think it would be a fun combination, its worth trying.

[unseen]

I don't do any PvP with my team, it simply doesn't interested me.

As far as PvE there are some nice things about warlocks:
If you're in an instance and need to go back to town to sell/repair, you'll have a way to get summoned back.
3x soulstones + anhk means you'll almost always have wipe recovery (except when you forget to soulstone your healer, which I do constantly).
If you spec 0/41/30 your rotation is pretty uncomplicated.
Damage-wise they do pretty well.

I tried speccing affliction and it was a nightmare to be efficient. I could do it, but between tanking, healing and keeping track of dots it was a headache. If I let a dot or two fall off I'd lose track of what I was doing and it would cause problems. Nowadays with 0/41/30 it's a simple rotation that does decent damage on trash and bosses and it keeps me sane.

I'd suspect with totems and blessings your team would do pretty well PvE-wise.

Edit: (Sorry, didn't realize you were comparing this to a 4xshaman + tank group).

As far as a comparison to the tried and true 4xShaman + tank group I'd say the biggest thing you'd miss is Heroism/Bloodlust. Honestly, I think this is the biggest draw for this team. With this you can bully down bosses you'd normally be undergeared for. In my opinion this is the biggest reason that these teams are so successful.

[Dominian]

Prot pally,3 locks and a resto shaman should do well for pve, when your 80 you wont lose to other 80's unless your wearing green/blues. A warrior/rogue might manage to aoe you down if your not pvp geared.

If you go 41/30 you get felguards and tbh they are awsome for boxers due to its fire and forget.

They are handy on bosses like the prince in UK who casts frost tombs, you can simply add a button called /petattack frosttomb and you can keep on casting focusing the boss encounter.

Personally i dont like multiboxing with pets since they tend to go on unintended missions(well ofc its me hitting the wrong buttons) and aggro but i guess this can be avoided! :P

[Moorea]

I have pally + 3 locks + priest as my first pve team - I left it linger in the upper 60s while I got my second team (DK, 4 shamans) to 80 but I will soon get back to it (after I farm some gear/money/... on the highest team)

I had specced my locks 1 of each spec - it does get a bit difficult to get good rotation and 1 of them mostly serves as softening up for the others ("utility" debuffs) - I'm tempted with going with 3 demo to soo - as for my priest he was shadow for a the longest time then switch to holy to try to do better at healing the tank but maybe for levelling rest of the way I'll get back to shadow (and hope the dmg->heal spell/talent I don't remember the name of will start to prove useful)

[daviddoran]

I have a pally/priest/3x mage team, and I am currently instance leveling 3 locks in place of the mages. It's very interesting to say the least. Mages have lots of instant burst, while locks have the dots, and strong damage sustained throught a fight. Right now they are affliction, but at 80 im going to respec (or maybe dual spec) to 0/41/30. As affliction they have some decent self healing, and have nice utility pets. I used to have them as deep demonology, and it was awesome to have such passive dps from the felguards. I mostly went with this team because they were there. Leveled them initially just to fill 5 spots when I was boosting a second paladin (in an ill fated attempt to create another paladin to be used to boost toons on my main account) Then I wanted to level other toons, and the locks were at the same lvl, so I leveled them again. Then they just happened to be my highest level toons that werent on my pally/priest accounts, so I leveled them again. I guess you could call them the red headed step warlocks...