I have a 105s and I agree with EVERY SINGLE THING you have said here. Every time I hit a defensive shot with the backfoot, the ball sails long. If you stay on top of it and drive, it is sublime.
I also agree it is not 2HBH friendly, I did notice that my 1 handed topspin backhand worked fine. Perhaps I need to experiment with that more.
I am going to replace the current 4G full-bed with a gut hybrid. Hopefully, that will provide a bit more control.