Dave, I would love to see some more comments about this, because as far as I have read, no one has reported any noticeable differences in the several 'different' ones that are out there.

IMO it is more based on how you drive the car, and what condition your local roads are in. If you race and autocross, 5-10K miles is a good life for a part with this function, after all, we are talking about a $30 part and most guys go through a $1200 set of tires in 10-12K miles.