Well I'll bring AivlaSoft EFB as example once again here, because their connection between main app and FSX is perfect, but they're using SimConnect instead of FSUIPC, so maybe that's the case, if that can't be done what about connecting to PFE from FSX menu, would that be possible?
That would be awesome indeed, but I think that would require rewriting big part of PF2K code into PFE, of course since we're stack with FSX for at least next few years I think that such effort could bring profit.