I can't help you with life expectancy I'm afraid but I'm astonished at how resilient they seem to be. When I purchased my Brooklands Edition a couple of years ago I was concerned to find that the belt had an 8mm dia. hole in it, presumably the result of a pebble or something getting underneath it. I have covered a few thousand miles since and although the MoT examiner found it and made suitable comment, the size and shape of the hole hasn't changed and I continue to use it with confidence.(but I did buy a spare when I saw one on special offer!) I'll be interested in better informed responses to your question.
