I thought there would be some responses to this. I have been using the 250s with my 20.1s. I auditioned Bryston 7B monos (not the 28s)and the AYre MX-R. Given what I wanted out of a system, the Manleys made the grade. The Brystons were very good, but ultimately uninspiring, and the Ayre was way to cool for me, almost cold.
I don't have any of the stock tubes in the amps. As I have an all tube system, and all Manley (300B pre and Steelhead), I have been able to exactly tailor the sound to what I want. And that's fiddling with all of the tubes in all of the equipment. I would never have been able to do that with solid state (well possibly with enough auditioning, which is really hard to do).
The 250s handle the 20.1s very well. I listen to all types of music, though mainly jazz, some opera, classical, ok a lot of rock too. I have never felt them deficient because they only output 250 watts.
I know there are people on the forum that say "only use solid state and make sure it is over 500-600 watts to get the best out of them. I don't completely understand this, though I assume it is what you are looking for in sound. I did not hear much of, if any dynamic difference between the 7Bs and the Manley that were important to me.
Check out the Manleys. You may like the sound. And remenber you can tweek the sound in many directions with Tube changes.