I have raced on the 2011 SLR all summer, trained on them a bit (including the 500 km break in period) and my wheels show zero sign of wear and no scratches after about 2,000 km. I have ridden them on dirt roads, including one nasty day above Boulder with lots of rain on dirt roads, with mud, and big descents, and still no wear signs. I highly doubt they will look great forever, but in Mavic's defense that is exactly that they tell customers.
So far I am totally happy with these wheels and I have to say the Exalith brake coating is the best breaking surface I have ever used on the road, bar none. Once properly broken in they work better and you can stop faster. Twice this summer I have had a rider go down in front of me in a corner, at full speed, both times I was on the brakes very hard, and was able to come to a full panic stop, before anything bad happened to me. I do not think I could have stopped anywhere near as quickly with regular rims. The rims also work better than a standard option in the wet, they start to slow down much faster, without the normal delay, the breaking force is much more progressive, and it does not die out as much as a regular set up.