Quite a few rides are in the wet, probably 1 in 5 on average. The wear markers on the rims are small holes rather than a groove which goes around the entire circumference. I can still see a small hole but obviously the depth isn't what it used to be. I have done quite a bit of research on discs for road bikes and when I next upgrade my commute bike this is the route I'll go down, however, being the tight person that I am I dislike getting rid of a bike before it is worn out or broken. It really is a great bike. I think my options will be a new wheel set (taking on board comments already made in this thread I'll look at some of the rims mentioned) or getting fresh rims for the set I have now. Given my commute terrain and the high speed descents involved i will replace wheels sooner rather than later. Thanks all for your advice.