A few months back I was looking for speakers to use with Eastern Electric Minimax separates, 8 watts per side. I passed on a pair of Galante Audio Rhapsodies which are a coaxial speaker w/ a 95 dB rating and are fairly large bookshelves but are highly regarded. They are no longer manufactured but come up for sale occassionally on Audigon.
When I talked with Sean @ Zu about the Tone bookshelves, he steered me towards the Druids as being a better fit. I felt they were too expensive for my budget and probably would require an upgrade in electronics because of their very high sensitivity.
The previously mentioned JM Reynaud Twin Signatures were also high on my list. I think Zybar on this board has or had a pair of the earlier models in his HT and is very positive about them. Maybe a little less sensitivity than you are looking for, but again highly regarded at a reasonable price point, probably would work w/ medium power tube electronics
Cain & Cain has introduced a miniature version of the Abbey called the Noogi which have gotten a nice reception on the Asylum but I haven't seen an editorial review yet.
Hope this helps.
BTW- I bought a pair of Vandersteen 1C's for a ridiculously cheap price and @ 90 dB they are a nice match. Probably wouldn't have a high WAF however they are extremely musical.
Edit:If you you have an interest in lower power amps, Louis Chochos @ Omega Speakers Systems
http://www.omegaloudspeakers.com/ markets very high quality mostly single driver speakers that people I trust highly endorse. They might even pass WAF.