I realize the CoolSoft synth isn't a direct replacement for XG, I love using XS for the realistic sounds that Yamaha used.
From past experience using midi, I found a lot of soft synths use tone generators and adsr filters, which to my mind is not realistic enough, whereas, digitally sampled sounds from real instruments sound a lot better than tone generated.
I also, used to use my keyboard for live gigs, but hooked up to a Yamaha TG100, and a laptop running the standalone virtual B4 and using the keyboard as a midi controller, simply because the 500 does not have that rich, 'Leslie' Hammond B4 sound that I can get with the virtual B4, using the far left E and F keys for Leslie slow/fast control.
Using an external wave sampling tone generator, has a huge advantage over using the 500's internal sounds, in such that live performance is better with the external generator and practice sessions using the internal sounds, also when using a laptop running various virtual synths, including an ARP2600, I can have the laptop next to the keyboard and using the F keys much like the 500's registration memory, I've performed a 3hr gig that way.
Anyway, being that the CoolSoft synth has problems with processing pitch bend data from BiaB, I found that I can create a rhythm section using BiaB, and export each instrument as a wav file, then import them 1 at a time into Sonar, which Sonar has no problems with the Coolsoft synth, which reminds me,,,,it's only BiaB that has the problem with the pitch bend and CoolSoft synth,,,Sonar has no problems using the soft synth and recording the pitch bend as it should.