I have one as well. Its essentially not noticeably different functionally from OEM in the slightest except its $300 instead of $500, and as said, its rebuildable.
Its a good solid piece of gear, effectively making the OEM obsolete, unless youre a total BMW purist and must have only original crap.
Actually- I will say that its probably functionally better than OEM, because the advance unit is now electronic as opposed to the stock's mechanical,, where the springs and lilbits could break or wear out eventually. So now that it has no moving parts it should be pretty much impervious to the ravages of time except for extremes of heat.
"Why BMW? You like to suffer? My sister, she has five kids, no husband. You come over?"