Thanks for the update!
Do you know whether it's a fundamental limitation with the DR-2X, or more of a question of additional engineering on your end? I noticed from the manual that EXT ports 1 and 2 are interpreted differently on the DR-2X, which would certainly break things; are there other issues?
On a related note, we were about to send one of our DR-1X units with a UDRC-II attached back to Yaesu for an update; should we hold off because of potential issues, or are the problems you observed specific to the DR-2X?
Paul Milazzo, K3PGM