1. Are you sure the OFH Gasket is not leaking?
I just did the OFH Gasket in my 2006 X5 M54 with 115K.
I also have a 1998 528i M52, the oil pan gasket is bone dry at 155K miles.
2. Now if you really want to get into this oil pan gasket, over E39 forum we pioneered the "cut and RTV" technique. No need to drop subframe. The BMW purists will say this is not kosher, but the practical people who did it told me 4 years later bone dry with "cut and RTV" technique. Here is the thread that "Mudbone" started in E39 forum...
Replaced oil pan gasket - Bimmerfest - BMW Forums