Yes this is in theory CORRECT and was so throughout wrath.. BUT cataclysm brought in NO new onehand enchants worth mentioning, and the stat loss from going 2h --> 1h is about 66% is quite great aswell..
the thing is agility is worth SO much more these days that it used to be, which is why it puts it in such an icky position of having to gimp a serious amount of agility (that we really do want) for being able to NOT be disarmed..
PERSONALLY I'm rolling with double polearm, one with +130agi for not being up against sp/warr/rogue and one for when I AM up against them.. it pains me to HAVE to do this, but it's simply the best solution as it is.