In reply to Wee Davie:
I have a border Collie who really enjoys cragging:
Walk in- longer the better for him!
Generally explores bottom of crag
Comes to whistle if other people turn up
Scrambles up to mod to meet you at the top
Always gives a sympathetic lick for a dnf.
Training was not very complicated- lots of walks, runs, one handed whistle to come back when needed. His only weak spot is cats, but they're evil and not commonly found at crags.