Hi Schakeel.
I hated the sequencer on my 9000 pro, also. Recently I got a software sequencer YamahaXG Works, and it's great. Only problem is I think Yamaha have discontinued it ( WHY!!!) There may still be the odd copy available.

It works really well with my 9000 pro styles. Simple as , type in Chord Progression, Choose & type in Style Parts ( Intro, main etc) Expand the arrangement into midi tracks. From there I can edit the tracks and add extra tracks like melody etc.
Bit like Band in Box except you're using Yamaha .sty files. This is the most exciting part of the sequencer for me. Of course it has all normal sequencer functions as well.

Not sure if it would work with the PSR2100 styles. I suppose it would depend if the styles have the .sty extension.

best wishes
Rikki