Got some new parts and did these three mods tonight before tackling the External Audio In one:
http://www.youtube.com/watch?v=32rDZ5IdLewAs mentioned, the resonance can be deadly (ears, equipment), so one should be careful with it: either set the patch resonance to 13/14 or else use some form of limiter after the synth output. It's super loud when self-oscillating.
I really like the new sounds when the Filter is set to 12dB. They must be closer to some of the Roland synths.
I'll probably do the FM Mod and the External Audio In one next.