--Has anyone used these? Are they as easy to operate as the ads make them look(one-touch reconfiguring of a complex home theatre)? I'm thinking hard about picking one up so my wife can "just watch TV"-- will I be making a $300 mistake? Input, please--

The initial setup is key--make sure you use the right systems in the setup (web based, 15-30 minutes depending on # of items and such).  Then test it....thoroughly.  Once that's in place, you can then have 'one-touch' type stuff. For example, you hit the "Watch a DVD" button.  Turns the stereo to DVD, the TV to  input 2, if the DVD is not on, powers it on, and hits 'play' on it.  That's all programmed by the first setup.  You can customize those a tiny bit as well.  If you have TV sound via external stereo, for instance, it won't adjust the TV volume ever.  

I got one for Christmas, the 880.  I love this thing.  

It took me a while to set up, mostly because we have two DVR's always on two monitors, with the main TV display being switched back and forth between them.  The harmony wanted to turn off the DVR that I wasn't currently watching.  It took me some time to find the option on the website to leave on the components I'm not using.  That fixed everything.  I spend probably about an hour total and programmed it for 6 TV's, 2 DVR's, 2 DVD Players, 2 VCRs, 1 Amplifier, and 1 CD changer.

As to what the previous poster said about the TV volume, on the 880 there is a "devices" button that is separate from the "Watch TV" button, etc.  If you click that, then the TV, then the remote will control the TV volume and not the Amp volume.  When you want to get the remote back to normal, just reclick the "Watch TV" button.