I've run 4x Hunters + Disc Priest for over a year now and, honestly, I've concluded they are just severely underpowered relative to the Tank/Shammy teams. Our guild stuck our heads into Naxx 10 last night, and although I'm not geared/specced specifically for raiding, I have a pretty solid gear portfolio on at least one hunter (prolly spent ~15K on AH purples). Anyway, my team was only pulling down around 6.5K dps (1.5K per hunter and much less on the priest). Some of that will improve with higher Hit Rating and such, but it's just not comparable to Shamans, and pet tanks are no match for a real Pally or DK tank for aggro and mitigation.

The hunter group is ideal for dailies ($$) and world event stuff, or even blasting lvl 80 5-mans. Maybe even farming a heroic boss or two (though I haven't tried too many) but their bag of tricks is just so much more limited than Shaman (totems, elementals, heals, etc.) that I don't see how they could possibly keep up.

Anyway, I may do some more testing before I totally abandon that team to gold farming, but even with recent pet buffs, the picture ain't pretty, imo.