Something like this would require Combat Reflexes in my opinion, and maybe even Uncanny Dodge. Whilst that does restrict those who can use it, why should anyone else have the reflexes to do something like this? A rogue would definitely have the potential to do this, and a barbarian "could" do it, especially with his higher speed.

Your standard paladin or cleric in full plate? Not likely. A dwarven fighter? Nu-uh. Not gonna happen. Your wizard wouldn't be willing to do it, he probably wouldn't survive. So that leaves the Barbarian (definitely going to survive) and the rogue (plenty of life saving class abilities at higher level).