ok for trash you are right - pushback allows others to take aggro. However boss fights pushback sucks when its a dps race (Hi, Selin fireweaver I'm looking at you.) I guess it will require you to actually heal instead of going all out on the trash (which I do in MgT -dps til its dead and then heal.) Of course this is all theory until I try it out. Also another good point, its 70% reduction - meaning with a few mobs beating on you at least ONE will get a pushback on you allowing other shaman to get aggro.

Another thing with ToW and FT Totem - I looked at WoWhead.com and FT WEAPON is still the lame fire proc on beta(useless to us)... so I'm guessing FT Totem and ToW don't stack??

edit: NM I'm wrong I missed the +spellpower with proc on FT Weapon. So then I would say one shaman in group specs ToW for max ownage.