And yet you didn't??

I think that, assuming the travel patterns work - and it sounds like the will for you, most folks would value UA 1K over DL Diamond. Even with the W+ fare requirement on the SWUs the UA version is easier to use than the DL version.

If you're not getting domestic upgrades anyways - one of the few areas in which DL is supposedly very strong for top tier - then I'm not sure it is worth sticking around, particularly since you are not a hub captive.