No mixing on them yet. Will probably use them for cross referencing. Not to disagree but nearly every thread about NS10 amps lists the 2B first and foremost. I think Andy also uses a 2B.
Every thread list the 4B not the 2B.
More power result in more headroom, so less chance to blow tweeter with distorded sine wave.
Andy use(ed) the 4B, sorry again.
You can use a 2B, but one per speaker, so you need two 2B, so for the same price you can get an used 4B.
Btw in case you didn't know that, Bryston have a 20 years warranty for their amp.
In all honesty I think the power rating is going to affect things the most. As long as the amp is flat and powerful you'll be fine; the whole gearslutz wankery over $1k+ poweramps is bollocks to me. The things were hifi speakers, for crying out loud!
I love most of your post, and I agree with some of your opinions...but class A amp cost money (especially high wattage amp).
NS10, as some others speaker are really picky about what amp you use to drive them.
And as far as I love my 3B, Bryston amp aren't really hifi amp. Try a Krell or a Passlab and tell me what you think about it (those are hifi amp, you can also find in any major mastering house around the world).
But you are right on one big thing: flat, powerfull and low thd amp work... But those cost money new.