If the sales information can be trusted, the second stage was redesigned and exhaling is easier due to the new exhaust valve. That seems to be part of where the better WOB numbers come from. For my part, my TX50 gives me all the air I've ever needed, so I don't know how much is useful and how much is over-engineering that you'd never detect in the real world. That's why Phil's test on TDS was so useful, IMO. Pop over there and read it if you haven't already.
As to the ports, the 1/2" connector is mostly a nuisance, something people wind up having to work around. It'll be nice if all of their first stages go to the 3/8" industry standard, but I read elsewhere that Apeks would be required to resubmit all existing reg models like the TX, ATX, etc. in Europe for new WOB/CE testing if they changed the port for existing models. That would at least explain why only the new models are getting away from that one 1/2" port.
I've seen at least one design engineer from Apeks that occasionally reads the UK scuba message boards, and we had an Apeks employee login here on SB once or twice asking for input.
CDNN, well, hmm.... Maybe not my first choice for information...