Tvad,
long and interesting thread for such a straightforward question. Just about every speaker I could think of has been listed but I would make a few comments.
first I agreee with several posters that if 15w (likely SET) is your foundation, stick with a slightly more limited FR or supplement the LF. Everyone always gets all worked up about showing all the different ways 8wts can "bring down the house" the fact is that there is a difference between making sound at certain frequencies and making full range music. Don't misread, I am a huge low power amp fan, i just like to keep them within thier limitations. All speakers, even 100db, are happier in the low end being actually driven with power and a high dampening factor. Read Srajan's comments when he hooked his Zu's up to 60w pp. Sure he lost the magic to some degree, but the foundation to the music returns.His in room frequency response probably did not change at all.
I would stick with getting the most through proper room gain from a great two way with 15 watts.
As for the death of high end in the USA. Two words: China and Audiogon. And I am as guilty as everyone else. But that is a different topic.