In reply to Matthew Burton:
Depends on the person. I've climbed Diffs and VDiffs in trainers or boots, but also in rock shoes (when I've wanted to climb fast). Some good licmbers may be happy on VS in trainers. Newbies will want to do Mods in rock shoes.
If it's summer and warm, I clip sandals to my harness to walk down in. If it's not warm, I carry boots in a sack.