I really liked the Feastrex drivers, the Maxxhorn Lumination ($12.5 on sale) speaker with the 5nf driver, and the 9" field coil driver in a BLH ($24k drivers only) were on display. The 9" speaker really needed a big space to open up, but the 5" did pretty well for being in a little room.
The Lowther / Pass OB speaker was good too, that special dipole effect was there, but the system only extended up to 10k which took some getting used to, the bass lacked impact, and there was a midrange bump.... in spite of that they were a lot of fun to listen to, and easy to forgive the mistakes.
Cain and Cain had some horns with 6" Fostex Sigma drivers, with the drivers mounted on the wide side of the horn

They were huge, but not very deep. I forget the model name, but they were very good... especially good bass, but lacked the extension and sparkle of 4.5" drivers.
Not SD, but definately check out the MBL omnidirectional speakers. VERY cool... but I'll never be able to afford them. The sounstage is sometimes incredibly good, sometimes it places the sounds in strange places... the realism was astounding with some music. Also, you have to see the Cogent Horns, I posted pics on the thread about rmaf pics. GR Research should get the award for biggest system in the smallest room. LS-9s with monster Dodd tube amps in a regular sized hotel room. These speakers sound like they'd be at home in an auditorium.
Dave