Well, I did as I said and put Zynergy on my SL5600. This also worked first time (I must be living right!).
Impressions- for some reason this works much better for me than TheKompany rom. I had real problems with both hdw and software keyboards \"sticking\" (repeating letters) under tkc- this is gone now. Also task switching seems faster, though still not instantaneous like on a Palm.
PIM apps are left intact by Zynergy and sysinfo utility works.
For my uses I had to add ssh client and server from ipkg feeds, and a few other things. Works great!