I'm surprised I have not seen this on the boards yet. In the Beta overhand chop and backswing seemed like an interesting combo. Take a full round action, get a first attack with x2STR bonus to damage. If you hit take a second attack with x1/2STR bonus to damage representing a return swing with the 2 handed weapon.
From what the Alpha now states, overhand chop is now a standard action. Backswing is now identical to overhand chop, except its only on the first attack of a full round action, and gets a bump to x3STR at +11BAB. It has pre-reqs of overhand chop and BAB+6.
As it reads now, why would you ever want backswing before BAB+11? I guess it is intended so that you can get x2STR when making your +6/+1 full round attack, but I would view overhand chop (standard action same as a regular single attack) as already allowing that. Even the x3 bump I see as a level bump for overhand chop, and not really worth a separate feat either.
The 6th level barbarian with 18 Str:
Full attack:
+10 1d12+4 / +5 1d12+4
Raged:
+12 1d12+6 / +7 1d12+6
Raged with Power Attack:
+8 1d12+14 / +3 1d12+14
Raged with Power Attack + Overhand Chop(Beta Standard Action):
+8 1d12+16
Raged with Power Attack + Backswing (Beta Full Attack):
+8 1d12+16 / +3 1d12+14
Raged with Power Attack + Overhand Chop(Alpha Full Action):
+8 1d12+16
Raged with Power Attack + Overhand Chop + Backswing (Alpha Full Action):
+8 1d12+16 / +8 1d12+10
Assuming my example is correct, while the Beta version will allow more iterative attacks, I think the Alpha a more interesting version when it comes to combat choices. The feat name "backswing" makes sense in that version as a second attack with the return swing. In the Beta, its just another damage booster for the first iterative.