I've got two (2) 880's, one controlling my 622 in the family room and one controlling the 811 in the bedroom. I think the 890 will work with the 622 for the 2nd TV if you setup your 622 for that. I've got my 622 feeding the computer room and I just use the remote that came with the 622 to control the 622. I don't need all of the extra functionality in the computer room to warrant the cost of the 890 (about $389).
Configuring them is easy. You setup an account at the Harmony (Logitech) site and build your setup (you need an account for each remote) then download it to the 622. It keeps a copy of your configuration online so if you need to make adjustments, you just login, make your changes, and then download the new configuration.
My family room unit controls my Sony, the 622, the DVD player, and the stereo receiver, the one in the bedroom controls my 32" HD LCD flat screen (Vizio), the 811, and a Sony DVD player. Nice thing is when you go to set them up, every possible piece of equipment is in their database and they have all of the codes for them already. If you do run into something that isn't in the database, it has a learning function. The online setup process will help you setup items not in the database.
By the way, I picked my 880's up on Ebay and they each cost me about $100 (new).