Do you know if any of the cheaper Harmony's work with it? All I have is an HDTV, the HD-DVD player, A receiver, and cable box. So I don't know if I need the higher end 880. Cant figure out the differances in the remotes too well. Any help would be greatly appreciated!
Yes, of course they will. Any true universal remote that has learning functionality will work with any piece of IR controlled AV gear you get as long as it's not using some really odd protocol or transmission frequency. It is only the ultra cheap preprogrammed-code only remotes that have trouble with newer equipment that isn't in their built-in database; these are better called "multi-brand, multi-equipment" than "universal". All the Harmonys are true universals that can learn, and also download from their online database which is continually updated.
The Harmony remotes are all very similar in function; the only big differences are size/shape/button layout, which dedicated buttons included, and LCD type/size/num buttons provided. Some minor functionality differences only with the sound, picture, media buttons not included on all of them; all the major functionality is identical. Compare pictures
You might also want to look at the Harman Kardon TC30 - it is based around the Logitech Harmony technology and has the colour screen and spec of the Harmony 850 but the design of the 520. I sold my Harmony 850 to buy it. It uses the same web setup as the Harmony too. It took me less than 5 minutes to add my new HD-A1 to it.
The default delays between IR signals are set very conservatively to try and ensure that things work. If you go to into the device options, you can adjust the delays, particularly the "interkey delay" to get it to work faster.