I’m only 4 or so maps in, but I got to wave 60 with just Duos, Arcs and anti-air guns on the desert map. I stopped mostly because I was bored waiting at that point :P
Maybe that’s too early to tell, but I desperately need a fast-forward button and so can’t be bothered to stick around for me :)
(Also, on the face of it, I don’t feel that it’s a hard problem to solve: all generation is in terms of X/second. Just give me a ballpark figure and I’ll probably accept it, even at 20% loss due to poor calculations!)