I can confirm that the kext in post 14 works for me in Mavericks, thanks sfr2 for uploading it.
It also seemed to fix the Airdrop issue I mentioned in my previous post for the Z77-DS3H, after installing it, Airdrop worked.
HOWEVER, oddly when I then removed it and reinstalled the original multi beast version, my Airdrop has continued to work, so I don't really know what to think there.
In conclusion, the kext works for me in 10.9, gives higher maximum (but much more variable overall) internet download speed, and may help to solve an Airdrop issue for those with the Z77-DS3H mobo (for reasons I can't explain).