Starkeeper,
As you probably know I own the EXR-7. I agree with you to some extent, but I want to explain some things about the EXR-7:
The internal speaker system sounds very harsh on all tones. When I'd bought it and put it up and turned it on, I felt exactly the same as you. It was not a pleasant feeling when you knew you'd paid a lot of money for it (I hadn't been able to test it before). Anyway, when I connected my good headphones, the sound was totally different (maybe due to the increased bass). Most of the sounds sound really good through headphones.
So my conclusion is: the on-board speakers are bad, or at least, not really designed for the sounds the keyboard is meant to produce and as the EXR-7 has no EQ, there isn't much to do about it, but I'm still happy with my EXR-7.