I think it also depends on which engine we are talking about. Most of the CP failures seem to be with the N55's. The N54 CP seems to be ok. IF you are running a "piggy tune" that are known for maintaining poor target boost pressures... a CP is a good idea.
I have been running a German flash tune(1bar of boost/14.7 psi) for about 65K kms now. No problems with the stock CP. I have been thinking of upgrading it though.
