Update: Through the dealer who sold me the player, I was able to contact Cambridge Audio directly and ended up trading in my 751BD for a substantial discount on a refurbished CXU. I had the option of trading up to a CXUHD (their newest model) but after reading up on these two players, I saw that the CXUHD contains no DAC circuitry and even though I use an outboard DAC anyway (Bryston BDA1), listening to my SACDs would be a problem because though I could listen to the CD layer of the hybrid discs, I have a few in my collection that are SACD only and the Bryston DAC isn't DSD capable. I may be missing something here, but the CXUHD doesn't appear to have a way to convert DSD to PCM the way most SACD players do.
Of course my new CXU has a lot of interesting bells and whistles (including Darbee video processing) which I may or may not actually use, but generally I do consider it an upgrade from the 751BD. High marks to Cambridge Audio's US representatives for the excellent customer service I received.