i have a pair of v8s and a pair of v12s the v12s are much better i haven't ever had to service them in three years the v8s require a lot more attention
i got V8's on my dh bike and they are pritty gud. you dont have to pay them that much attention at all, the only attention you give them i grease every now and then which is like a 2 min job! then just fit and forget. the only problm i have with them is that the platform is not quite big enough for my size 11/12 feet!
I have them on both my bikes now They are really grippy, I have only ever slipped twice in total on them. Mine run really smooth and i havent greased them in ages.