Rikki, just design your own GM/XG wavetable and use a softsynth. The sounds will be much better - plus it is very easy to carry around, i.e., the bits weigh 0 pounds. A midi controller keyboard weighs less than an arranger or workstation. Therefore your net loss in weight could be many pounds. Rikki you can't lose.

In fact, I would say the Roland HQ Hyper Canvas 26mb wavetable sounds better than the 4mb Yamaha XG, i.e., virtual acoustic instruments sound closer to the real acoustic instruments. Now with OMB you can convert the Yamaha drums in the styles to GM and use this wavetable.

You see if I keep at this, Rikki will just give up and use a dumb keyboard and a computer to do everything and do it much better. It could happen!!!