Every VANOS has thrashed seals. The material the original seals is made out of is simply not compatible with the operating environment, they're certainly not compatible temperature wise and possibly not compatible chemically. Definitely do the seals if you're in a position to do them; they don't even last 10k under normal operating conditions before the symptoms occur, the software just masks most of them.
I was one of the first people here other than the guy selling the seals to do them... was way back in early December of 2007. Unfortunately, I totaled my 328i 2 weeks after replacing them but the difference was noticeable even before they were broken in.
I plan on getting them done on the 330i insurance replaced the 328i with as soon as I figure out a way to get the third party warranty to pay for a VANOS replacement... getting the mechanic to order the replacement from DrVANOS instead of the dealer is easy, but finding something actually externally wrong with the VANOS (better yet something that throws a CEL) is going to be tricky with some of the extra crap the M54 DME does to hide the problems that the M52TU DME just doesn't do.
