Hi,
I have purchased and owned a 5.5 uni and two 5.5SL's - great boats!

My advice, for what it's worth:

If he's not racing, he can do what I did when I was not racing - eliminate all the criss-crossing wires on the trampoline (the shin-scrapers) and mount a block with a cam-cleat directly to the forward-aft traveler track(s). (like a Nacra 5.8) I would leave everyhting else as-is. (And of course, add a jib furler, as both my 5.5sL's had)). A smaller-higher jib will not make the boat any more stable or easier to sail, and the pin-head main is fine too. Why spend so much money if it's not class-legal and dosen't make pleasure-sailing more pleasurable? Take that money and buy a cover or cat-trax or aluminum trailer or self-cleating Oxen blocks - or a lighter mast maybe...

Steven Bellavia
Hobie FX-1
Sail #211