Shim
I have been down this road with limited success, however, I am an old guy that isn't very proficient with midi software.
I bought a Muse Receptor and loaded it with B42, Collossus, and Kontakt. I use an Axiom 61 controller,but a keyboard with good midi implementation will work.
The sounds were pristine for sure, but had no facility for rhythms. The only other thing was trying to get the proper modulations or articulations with CC control.
I just got a fast i7 laptop and will try again.
My best success is the vArranger, which is a hybrid in that I use a Ketron SD2 module, but it plays Yamaha styles as well. The sound source doesn't have to be the SD2 if you have a fast enough laptop, but is was written originally with the SD2 in mind.
This program is rock solid, sounds great, and even I have no problem taking it to a gig by itself.
Bernie
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pa4X 76 ,SX900, Hammond SK1, Ketron SD40,Ketron Event X Centerpoint Space Station, Bose compact