I don't know about the grip size, but it would seem to me that the grip angle would have to be the same as their respective pistols, to allow for proper feeding.

Perhaps someone uber, who has both can post a side by side?

 

I would also assume the grip angles would have to be the same as each pistol but I was hoping someone could tell me for sure.

Well, since the Glock and Beretta angles are different and I have shot each type I think I might go with the Beretta. It felt better in my hand when I shot the pistols.

 

The grip angle on the Glock models seems to be a little more upright. This is most obvious with a magazine inserted. You can see a slight upward angle at the front of the mag floor plate, while I'm pretty sure the mag floor plate is on the same plane as the pistol's barrel. I have a G22 model, no matching pistol, although I have handled one. I imagine the G17 is the same way since I understand they are basically the same pistol with a different slide/barrel. Can't help on the Beretta models though.

:-/