There are guys who use the Seemiller grip and play an all out topspin game. The grip causes the racket to be closed easily for FH and BH so topspin is pretty natural without having to do as much to adjust your wrist to close the racket. I think it is actually closer to some tennis grips that are used today than the traditional shakehand grip. But the Seemiller grip does make it really easy to twiddle for those guys who use it.
Shakehand grip: FH racket closed by forearm pronation and wrist extension:
Shakehand grip: BH closed by forearm supination and wrist flexion
Seemiller grip: FH closed with wrist and forearm in neutral position:
Seemiller grip: BH closed with wrist and forearm in neutral position.
Biomechanically Seemiller grip is much easier on your elbow joint than shakehand grip because you don't have to do anything to close the racket for FH or BH topspin.
Personally, I can't play with the grip for beans. But that is because I am so used to turning my wrist and forearm for the FH and BH shots. But I have a friend who plays shakehand who can switch back and forth from these grips and play all topspin and play pretty well with either grip.
However, he can also, with a shakehand grip, turn his palm up and hit FH loops with the BH side and the loop is as good as with the normal side.
In the end, I think it's all what you are used to.