if they leave the difficulty level of the 5 man first encounter (vehicle fight) where it is, it'll be fine. It's completely doable as a multiboxer. It's completely trivial now for a normal group though (more difficult to box, 1 char always seems to get focused so he loses all his shield charges but not impossible) so I would expect they might tune up the encounter some. If they do ratchet it up I'll probably just get one of the other multiboxers to run their tank with my shamans, and I'll do the same - then have the tank kiting the main hard hitting dudes on the first encounter while zerging the adds.

For those that haven't seen it normal mode is pretty much killing 1 commander 3 lts (like in the daily) in waves (same argent mount mechanics). It is zergable. Heroic might be zergable too, but I died pretty horribly trying to - only made a couple attempts though. You can hop off your horse and grab a new one at any time and (most of the time) it resets/reduces the agro on whatever is currently attacking that person.