I tend to side with the more straight armed 2hbh players, such as Nadal. While it is a marginal difference, the 2hbh is already limited in power because the off hand is chocked up on the racket. Bringing it closer to the body just reduces the ability to develop racket head speed, though it may allow for more control.
The straighter left arm bent right arm (righty) is closer to a left-handed forehand, and superior for spin and power in my opinion.