I listened both the MP3 and Midi-file.
On some points Captain Proton (Electron's brother?) is right.
The singer is pretty much out of tune some times (nothing to do with OMB)
The MP3 quality is bad because of low sampling-rate? (nothing to do with OMB)

I'm not sure what sound-source produces the sound.... the midi played on my Tyros sounds much better but the arrangement sounds .... well.... poor! IMHO (I'm sorry Jos)

I'm not sure either how/where to use OMB :

a. At home creating MP3's for performing? (Like Band in a Box)

b. On stage with laptop, masterkeyboard and soundsource ?

If OMB only is a software arranger that needs a PC(laptop), keys and HQ soundsource, I think the needed money will exceed 1500 Euros..... a brand new PSR3000 costs less