Anyone running Nexus 7000's without vPC to FEX's?

Hello,

Is anyone here running a distribution layer with 2 x N7K's, without vPC'ing to downstream FEX's and access switches?

I am having some exciting times after migrating from 6500's to 7000's (SUP2E, F2e to FEX, M2 to core, 8.4(3).

I am having ARP problems, i.e. ARP will be lost for devices that are singled homed, i.e. devices linked to 7K-A, will randomly stop being accessible from systems that are multihomed. This seems to mostly affect devices using ISR's (hanging off 7K-A) for NAT

I can describe it further and in perfect technical detail, but I want to get some feedback first to see if anyone is actually running 7K in this group

thanks for all