[quote=DonM]

The parts that seemed to benefit the most from stereo were the guitars, both as Right Hand sounds and in the styles, although I do have a special stereo string patch combination (two different string sounds) that really has a nice "bigness" about it when played in stereo.

The Electric Pianos that use stereo chorus (or panned delay) also benefit nicely, as do the Drawbar Organs that use the Rotary Speaker emulation.

When you think about it, all these arranger instruments were originally designed to sound at their best in stereo, so there is bound to be some loss when played in mono.
Ian