Best to wait until at least one day passes probably.
As of right now PCIe 3.0 doesn't do much to enhance card performance, but higher bandwidth is generally a good thing. Especially if new cards show up that can utilize it well.
PCIe 3.0 is backwards compatible, I think. Sandy bridge will can use those cards, just not with PCIe 3.0 bandwidth
The motherboard and chipsets can provide ways to get higher mhz for your ram. Right now though higher ram speed than 1333 only effects Trinity APU's GPU in any dramatic way.
i know ram speed isn't that big of a deal, but the whole thing about "future proofing". might as well