If you do look at the MX-800, you'll have a hard time finding the programming software (Universal's pulled all of that material from their site, so that they only way to get it is from an authorized dealer). Of course, old copies are still floating around the net . There are a number of satisfied MX-700 and MX-800 users around here. There are also a number of Harmony users (not many with the newer Harmony 990, but 880 and 890 users are fairly common). A few threads come to mind:
harmony 990 and power up to radio?
Harmony 890 with 990
990 and Harmony 880
990/Harmony 880 issue...