Thanks Steve. I took a look at the casting functions and the one for DATETIMEOFFSET was confusing me. However, while looking around in there, I did see a NULL function of REPLACENULL. I had not used that before, I'm thinking maybe it is new. At least new since I started doing this. Instead of the Boolean NULL expression I was using, I used the REPLACENULL in the following expression:

(REPLACENULL(CompleteDate, "1974-08-28 08:28:49.0000000 -01:00") != (REPLACENULL(LkUp_CompleteDate, "1974-08-28 08:28:49.0000000 -01:00")))

This seems to be working for me. Thanks for getting me to poke around in the functions!