Sean A. - it's funny that you mention Machrihanish, which (as a member) I was delighted to call my everyday course precisely because it was a) marvelously interesting and b) didn't beat me up. But you know, there are people who are members at Dunaverty up the road who I've had tell me preferred their course to Machrihanish because the latter was too tough! I would certainly never give up my membership to join Carnoustie, although Muirfield might be a different story (although e.g. my friend Archie Baird, an elderly gentleman who is a member at both Gullane and Muirfield and has a delightful golfing mind, winds up playing most of his golf at Gullane because it's shorter and he's able to better tolerate its difficulty). It all goes back to my favorite golf saying: everything is relative...
Cheers,
Darren