The damage off of classes like ele at 920 is staggering in wPvP. But I wouldn't say you'd die in seconds if played to the max. Especially with a resto shaman. They're great MB healers due to spirit link totem, healing tide being shared on a 3m cooldown. That has saved me quite a bit when some random splashes into my team in wPvP.

I do like DKs for wPvP though for the reasons you stated. Melee uptime, grips, stuns, interrupts for days. And anti-magic zone is great when you are being cleaved down by magic. No other melee comes close for multiboxing.

If playing hunters this gets very difficult because they offer nothing in groups. All their defensive work is kiting. Warrior can smash something hard with warbreaker into bladestorm. I imagine 4x warrior doing that would decimate most any opposing pack. There are others like tanks that have crazy durability to mitigate most ambush attacks.

One team I still have interest in is a prot war + rshm + 3*ele. Lots of firepower in that comp. What wPvP really needs is burst and sustainability. This comp would do well.

For now I'm just 3 boxing my warrior + rshm + warlock. But I may get back into 5 boxing soon as it feels pretty dull only playing 3.