In reply to wannabeagoat:
I did a course a couple of winters ago and Martin and his guides are pretty expert (as you'd expect) at finding conditions, whatever the weather. They even have a dry-tooling crag to hand. His location means he can reach several different areas - Torridon, Skye etc.
The NW is definitely different - be prepared for big days out, but big rewards as well.
The atmosphere of the accommodation and catering on Martin's course are second to none and well worth the effort. Life would be very boring if we all went to the Cairngorms year after year
P.S. my instinct (with no evidence whatsoever) is that it is better to wait till Feb/March rather than go up there in Dec/Jan.
Post edited at 18:05