I never used any of those, but I've had lots of experience with the Yamaha all in one boxes. EMX line I believe. Pretty good sounding units for small venue live work ( as far a I can tell). These have separate monitor and main controls, 200 watts per channel, and the Eq is nice for notching out feedback frequencies.

You may want to head over to the 'live sound' forum on the main page of recording.org and ask there.

amazing.

small world i guess. I use a Sure Beta 58 as well for my vocals (live setting) and a KC 500. They recently came out with the 550 wich is a shade more powerful but essentially the exact same thing. I know a great deal about keyboards and keyboard gear... i use my amp mainly for keys. I have found that Roland knows how to do things... in almost all facets of their products (i dont know about thier new DAW though). From their old analog keyboards to their new digital pianos, accessorys and yes amps. They do make quality products that can withstand touring and abuse.

The cool think about the KC series is its features FOR live performance. if you want to use it for mostly vocals... then i'm guessing your playing at places that wont have a PA. Keyboard amps are pretty much just powered PA monitors. cut and dry. There is not really any difference in sound to the equivilant in a PA. but the keyboard amps do offer alot of potential with their added features. for example: 6 channes with XLR inputs, built in Direct box (to go to the main PA if your playing at a place that has them and you just want to use the KC as a monitor). EQ, stereo link! even...
the headphone out is clutch as well and is really one of the most important features i have found in my amp.

yamaha does make quality gear as well, but you will find the roland has more usable features and is a step higher in quality. the arched front is also a plus for monitoring;-)