what would you do if faced with the (...) choicesI prefer the sound of the Ref110 to the vs115. I've only listened to the 450 once -- so no opinion.
OTOH, experience with the other amps is based them driving small SF (the same pair, in fact!).
BUT when I had the Strads at home I only *just* drove them correctly with 250W class A SS per channel.
(Outstanding speakers!)
And the 450 offers the advantage of 450W of power / channel...
So, I would go for the 450. If I didn't the sound I'd look around to improve -- but at least I'd know it was driving my speakers correctly, if not to my liking!