I've just changed the springs, I'm still on the original (and about shagged) shox as I like a bit of ride comfort (and have to chauffeur my 3 1/2 yr old about). The springs make the handling better, and also enables you to do the lift off oversteer trick on wet roundabouts. Also enables your arse to fall out if you lift off on a diesel soaked wet roundabout, so be warned - I did a massive tank slapper barely staying in lane with 40mph oncoming traffic [:0][xx(]:I Springs were £70 I think, takes half a day to fit them yourself.
Ecotec valve - I know someone with a Cinq who has one and he reckons it's worth it. He says he gets better mpg and a little bit more power.
Mrs Crayon - have you chopped the bump stops? with a 50mm drop you'll just about be sitting on them all the time, I had to halve mine just for a 40mm drop, but the back end still bottoms out if you hit a bump in a fast bend, may be better with good shox though.
Pete.
Cinq sporting 1242cc
http://mysite.freeserve.com/close_to_cracking_up/