5-box for PvP and PvE: Possible with warlock/priest?

As many on this forum have discussed, it's a lot harder to build a 5-man combination for PvP than it is for PvE. I'd like to see if it's possible to build a 5-man team that is effective in PvP but can still run heroics by itself.

I'll start by going over the effective combinations for PvP:

From what I've gathered by reading these forums, anything with a warrior, rogue, feral druid, probably won't work because of melee positioning issues. Hunters sound good in theory but have deadzone issues. That leaves paladins (healing and AoE tanking), shamans, and cloth.

5 shamans - great burst/focus fire, healing stream+chain heal gives you good HP recovery, overlapping totems are powerful in PvP. Question is, can you run heroics with just earth elemental tanks?

1 paladin, 4 shamans - someone had videos of this being effective in Arenas. For instancing, the paladin can serve as a main tank.

1 priest, 4 mages - proven to be effective in PvP; mages have pom/pyros and AOE. 4 sheeps should make heroics possible, but what about pulls that have cc-immune mobs?

Other than these, the main possibilities seem to involve some combination of priests and warlocks. 1 priest 4 locks would be powerful in PvP, just because of the strong utility offered by the warlocks, plus pets, healing, deathcoil, instant-cast DoTs (don't need to worry about facing). Demonology-specced warlocks could theoretically tank instances, right?

The question is, is that the best ratio? What if you had 2 priests and 3 locks? One or both of the priests could be shadow, thereby healing the pets and increasing warlock damage. Or, you could use 3 shadowpriests and 2 warlocks - 3x shadowpriest healing should be able to keep 2 felguards alive as tanks. You also get 3x mind control for tricky pulls.

If you increased the number of priests in the group, how much do you think your effectiveness would decrease in pvp? Do you think any heroics would be possible with an all-cloth team?

Roll 4 locks (VW tanks) and priests on Mag - we are starting a guild. At least 5 of us now, 2 are 10 boxing.

aw man why can't that be on gorefiend I'd join with my little 2/3 setup :D

The only realistic setup you mentioned that could pull off some heroics is the 1 Paladin 4 shaman combo, and even then it would be difficult, but at least you have a solid tank and 2 healers + 2 dps.

Overall with those specs they wouldn't be effective in PvP at all - though a simple respec would do the trick if you already had that in mind.

Heroics aren't meant to be easy, which is why they removed them from being a requirement for guild progression into the top tier zones. In my opinion the overall time spent vs reward isn't worth it as well. I would build a team that can do normal runs successfully and get my gear through quests/ PvP rewards. Arenas give insane amount of top tier gear for low input.