the sounds of the mc-307 are really good!!!
/i've tried it 2 months ago...i have it at home for 2 weeks, but didn't buy it cause i've preferred the Yamaha RM1-X.../
it has the classic groovebox sounds , plus a lot of new brillant ones...new drum kits...more sounds at all from the other 2 g.boxes
the only bad thing is, for me, the absence of low boost knob: i liked it a lot in the mc-303 (<- i think, anyway, the best groovy machine ever!!!) and 505...
ciao-marco