I think if your some what geared some of the old wrath heroics will be faster per badge than say PoS (even on normal there still is a lot of trash). 2 badges from FoS, 3 from HoR... which you could possibly do both reasonably in about 40 minutes,and faster once servers stabalize and people start getting used to the pulls. So by comparison a lot of the old wrath heroics can be done by most in under 30 minutes. If your using the random heroic then you could see 7 badges for Gundrack or CoS or Nexus... which for 30minutes of blasting is hard to beat.

A lot of the shammy teams will be farming normal PoS for the caster shield, so I guess that would be the one I would keep running on normal. Once your all T9'd out and you have what ever drop you need from the instances... yeah most people will go back to doing the random heroic and then work on other things. Farming battered hilts would be high on my list (lots-o-alts). I have to check on trash respawn times tonight, PoS seems like the obvious choice for hilt farming to me.