I realize that there are a number of variables which determine how long a saddle should last (riders willingness to rid in inclement weather etc.), but I was wondering if I could get a few opinions on how long I should expect a saddle to last.

I currently have about 5,000 miles on my Terry Fly, and it is beginning to look a bit worn. I can't decide if I need a new saddle or if I simply have a jones to buy something new for my road bike (I know you all know what I mean by that!). Does a saddles ability to comfort diminish with age the way running shoes need to be replaced after 'X' amount of miles, or should the seat be replaced when the leather starts to completely peel off?

I've been very happy with my Terry saddle, but I have very little to compare it to. The Bontrager saddle that came with my bike sucked in comparison. In the back of my mind I'm wondering how much better it can be. The only way to know is to try different saddles out-- but at 100-400 bucks a pop that can be a very expensive proposition.

The Fizik saddle at my LBS seems to be calling my name.