I have been using the lnx2Mac RealtekRTL81xx.kext on my Z68X-UD3H-B3 (RTL8111E) in Lion for a long time, always great performance en no problems with it, big thumbs up for his work!
Recently I reinstalled my machine (from scratch) with Mountain Lion (U1H BIOS, 10.8.5, no DSDT...