Hamish,

The 5.11 pant was originally designed for rock climbing. I find them very comfortable to wear. The FBI, police, and fire department community have found them and sales have taken off.

http://www.511tactical.com/Products/Tactical/Pant.asp

I guess one reason for getting the UK survival was that it is a close match to the 5.11 pant in style.

As to the cost of your collection, I can relate. I have been diving since 92 and 3 years ago I made the mistake of tallying up all of the receipts for my gear. I do more advanced diving than most divers so my equipment is also advanced in price. Full face mask, communications, and dive computer alone totalled $5,000. As I don't smoke and support other addictions, I bought most of it while still considered in the low income bracket. It was very eye opening to realize that my gear cost a combined $10,000. And to top it off, I do not carry that high of a credit card debt, ever.

I am going to clean out the closet this weekend to make room for my kilts. I have a bunch of pants that I will never wear again. Maybe a yard sale is in order to make some money for more kilts :-)