There are three that I definitely wouldn't sell:
1 • My first 'proper' mtb, owned since new in '92. It's in bits and the post's stuck but it'll never leave me.
2 • The bike I always dreamed of BITD and am nearly finished fettling with.
3 • The bike that would be impossible to replace as there aren't too many about.
All the others I would probably sell as they don't really mean a huge amount to me. They would be tricky to replace if I sold them, but that's the only thing really I think. If it meant getting my 'Most Wanted' then I'd sell them all without a thought.
The parts thing is a strange one though. I couldn't sell everything as some of them would be needed to build the 'dream bike' wouldn't they?!
A lot of stuff though I have just hoarded cos it's NOS, and I don't want to fit it or haven't got anything to fit it to... Things like that I wouldn't have a problem with selling to fund the 'dream bike'. Again they would be difficult / impossible to replace, but they would have helped get me the dream bike.
Oh, and by the way - Jez has another bike (at least one!) which isn't in the photos - his original Lava Dome with Quadras!