Tvad,
One thing my wife and I have found with squatty flat-top speakers (like the Altecs I mentioned) is that they in effect raise the floor up thirty inches or so. They're not so tall that you can't put things on them, and when so decorated they blend into a room better than their width would lead you to expect.
I've been scratching my head about reasonably narrow, deep speakers with decent bass and smooth impedance curves, and Fried and Buggtussel come to mind. I was a dealer for the latter company, which is now sadly out of business. Both use transmission-line enclosures. While both have models rated at 4 ohms, with the Buggtussels at least it's an honest, resistive 4 ohms - still a relatively easy load to drive.
Another possibility is SP Technologies. The Timepiece 2.1 meets all of your requirements except efficiency. I like the two-way with waveguide approach.
Soliloquy makes tube-friendly speakers. I'm not real familiar with their lineup, but recall liking what I heard from one of their larger models at CES a few years ago.
How close to the nearby walls do you anticipate placing the speakers? Can they be toed in? Given that the Tyler PD speakers failed the WAF test, can you give us an example of a speaker that would pass, even if it doesn't meet your other requirements? If it turns out that you can't "have it all" at that price, in what area would you be least reluctant to relax your requirements a bit?
Duke