Today, I played the ProKeys[M-Audio's stage piano/controller..]
The first sound I tried was the Grand Piano..I read Keyboard Mag's review[high marks] and expected it to amaze me...Total disapointment..the piano, although a good tone, had no dynamics..Electric pianos were better to me, but lifeless..Basses were good and the ride cymbal was cool..Organs were bland and a poor leslie[mod wheel/modulation]effect.
Strings are nice, clav and vibes, okay..
As a controller, it lacks controll, unlike it's counter part M-Audio's top controller..
The Pro keys has the same keyboard/housing as the Top Controller model..It also has the same weight[over 50 lbs..]
The pro Keys rates a"I pass" from me..for others, a street price of $599..it is probably worth the price..but I still pass..