I feel with the launch of the GX7 I could now finally abandon full frame Canon completely, as I have an aversion to large heavy cameras. All I have left for the 5D2 is Zeiss 21 and 28 and Canon 100 IS macro, which tend not to leave the house.
I have a self imposed rule that any new acquisitions need to be 100% offset by sales. Currently have GH2, 20, 14-140 and 100-300 so only 20 in same league as aforementioned Canon/Zeiss lenses. I thought Panny 7-14 would be close (ish) to the Zeiss wide angles and the Leica-Panny 45 macro would replace the Canon 100 macro. Also think I could find uses for the Olympus 75mm.
As long as the macro is up to snuff, I'm fairly sanguine about "pixel-peeping" differences, as I've also got the Sigma DP2M and DP3M which have IQ beyond anything else I own.
One problem is I like to use 10 stop ND filter sometimes and the 7-14 has no filter ring - there are no M43 primes that equate to the Zeiss 21.