Ecclectique - regarding the Duevel's and Tannoy's. With respect to the Duevel's I've read some reviews on the Bella Luna and they sound very promising, with some inherent limitations. You can probably get some dealer info. from this site:
http://www.cd-konzert.de/loudspeaker.htm
Another interesting speaker design concept worth noting is the Oskar Heil A.V.T. (Air Velocity Transformer). Oskar Heil Speakers has recently introduced a new model called the Kithara ($4,900). The A.V.T. uses a lightweight diaphragm, folded into a number of accordion-like pleats to which aluminium foil strips are bonded. The Diaphragm is mounted in an intense magnetic field and a music signal is applied to the aluminum strips. This causes the pleats to alternately expand and contract in a bellows-like manner in conformance with the music signal forcing air out of the pleats and sucking in on the other side, the air movement is 5 times bigger than the movement of the membrane, therefore also the velocity must be 5 times bigger. The benefit of this transducer design is better differentiate sounds.
Tannoys! I've worked in the multimedia industry for over 14 years and spent many hours in professional editing suites in NYC, Los Angeles and Atlanta, so you know I've heard a lot of Tannoy professional monitors. The Tannoy monitors I've heard are absolutely fantastic, practically an industry standard in the '90's. However, I didn't think their floorstanding speakers were able capture the same magic, especially when I listened to them next to Vandersteen 5's and Martin Logan's. I thought my Hales T-5's were far superior to any of the Tannoy's I listened to.
You're right this is a very interesting subject. Perhaps the ultimate speaker is a hybrid that includes an active sub and mid-range and a 360 degree tweeter design.