Syncing with the RE is currently slow but fine/stable.
It's still a beta-version and there are reasons for that.
It's not a big deal, I've also got RM for W7 and I can use both now. Probably the Mac-version is still more buggy, but better than nothing. I'll try it on my notebooks (MBP + MBA), maybe it's more stable there. The only really disturbing bug was the changing of some profile-names without my participation....