I've had spacers for about 12000 miles on the 959 and 700ish on the V4, it's quite unfortunate that there was an issue with yours. The spacers are the best bang for your buck mod and if I rebuy, I'm definitely buying another set.
I have put over 1000 miles on my SL with the spacers and no issues. Of course, Brian at BMS installed them so they're probably his ones that were the original design, as Jarel mentioned.