I used to have an 8 on the commuter (just sold it a month ago), did about 1500-2k on it, not a single problem.
I also used to have (sold a couple weeks back) an 11 on the mtb. I bought it when they came out. Didnt have any issues in the 1st month or two, then the cable snagged and bent, which ment i couldnt get into 7,8,9 or 10 with out it skipping, a quick cable change and it was fine.
One thing i would say, i did have to fit a middleburn cable oiler as the return spring seems to be not as strong in the 11 when compared to the 8. So i regularly (every 5/10hrs of riding) had to spray a bit of GT85 down the cable. This may not be bad if, like me, you only go on 2/4hr rides but i could see it being a problem on ‘all day’ers’. It might just have been an issue with my hub though…..
Only reason i sold both bikes is to get one new one (although it doesnt have an Alfine).