The Sono 88 does not have an on board sequencer..but does have a GM wavetable..You can play sounds from the ProKeys Sono88 via VanBasco...

40 polyphony is enough to play piano/organ without any problems...even over top of a sequence.....if you do not lay on a hold pedal it will do fine..Not too long ago we used 24 polyphony (SC-55)...

and folks here still use the Yamaha 32 voice instruments..

The Sono is a controller...and a digital piano...with cool control right on the "dashboard"..