I've been sitting here playing with HankB's S900. Only thing it needs is better drums, particularly the rim shot. The rim shot on Ketron and Roland sound real. Those on Yamaha sound like someone hitting a desk top with a ballpoint pen.
As long as they put a vocal harmonizer in it, they should have put a good one. This one is usable, but barely so. There is a glitch every time you engage or disengage it, so you MUST never hit the switch while singing a note. Other than that, it can be tuned to sound "o.k.", if you are meticulous when setting levels and e.q. and where you position the mic in relation to the speakers.
DonM