Another quick update - the SG-2440 was removed from service about 6 months ago - office consolidation.
Pulled the box home - powered it up on late last week, and it worked thru the boot sequence and started up correctly.... did the pfSense upgrade to 2.4.4, and all seems to be good.
So that's a really cold boot so to speak...
Anyways - with coreboot ADI_RCCVE-01.00.00.17-nodebug and 2.4.4, seems to be working.
Still some concern about the C2000 series issue - the coreboot update should have fixed things, but still see a number of reports of no-boot issues on this board family here on the forums - not clear as all queries have been directed back to netgate customer support, and no further action on those posts...