Pros: Compact, self-contained, best sound of any keyboard amp available today
Cons: Big and heavy, and a little fragile
Stage pianos and B3 clones with a Leslie simulation sound best in stereo. In many cases, the sound quality of the instrument degrades considerably when heard only in mono.
Choices for amps are limited. As of this writing (2005), there are only three stereo keyboard amps on the market, and Motion Sound makes two of them. Otherwise, the choices are two mono keyboard amps, or a more elaborate, multi-component sound system, with a mixer and speakers.
The KP-200s is OK and is the best thing available if you want a stereo amp all in one box. It sounds good, though not great, and has enough inputs to handle four keyboards and a microphone. The plethora of special-purpose inputs has been well thought out. There is a microphone input, which is useful if you're making announcements, and is usable up to a point for singing. There are four stereo keyboard inputs, and a click-track input for cueing. There is a connection for a subwoofer, and some direct outs to feed a FOH board.
Shortcuts, however, have been taken.
The pots are not especially durable, and aren't mounted very securely. There is no reverb. The mixer is noisy, so you have to watch your gain structure more closely than you should have to. The direct outs aren't truly balanced.
The sound quality is limited by the two-way design, which won't accommodate the wide frequency range of a keyboard. The optional subwoofer would probably help, but is heavy and expensive.
The KP-200s is too bulky for one person to carry comfortably, unless your day job involves playing football or moving furniture. The KP-100s might be a better choice for someone playing solo gigs where it is important to be able to go up and down stairs with the amp, by yourself.
Now, all that said, this is still a very workable amp. It's great for practicing with a band, because you can be self contained and set up the way you want rather than having to share a PA with the vocalists. It's loud enough to compete with drummers who don't know how to turn down the volume. It is small enough that it will fit on small stages and in small practice spaces.