Looking at John Atkinson's measurements on the Stereophile site, that's not a very difficult load for an amplifier. All the amps you mentioned will drive them just fine.
Unless you are regularly listening at ear splitting levels and setting them up in a large room, quality watts of at least 20 or so would be appropriate.
I have Dynaudio 52SE running off a 20 watt tube amp and want for nothing. However, I've also run them with several hundred watts of solid state and they do like to go loud without breaking a sweat.
Dynaudio uses great drivers that can be played very loud and maintain their composure, so if you enjoy going loud, go for the watts. If you don't need the watts to reach your listening levels and are ready to try some tubes, you shouldn't let the sensitivity issue worry you. Most people are quite shocked at how few tube watts are needed to produce plenty of decibels.
Keep this in mind when considering watts. It takes a doubling of watts to increase the spl a mere 3 decibels. That means that the difference in a 50 watt amp and a 100 watt amp is only 3 dbls.
I'd suggest giving the Primaluna serious consideration based on its autobias circuitry. That takes a lot of the fear of tubes out of the equation for people new to them. Not to mention it's a damn nice sounding amp that is built like a tank. You'll find out real quick what tubes are all about and whether or not they are for you. If they don't float your boat, the amp is always in high demand and you won't take a bath on it.
