I can vouch for my good friend Dennis' (Badboss429 - wish you didn't sell that Boss 429!) enthusiasm over the Quicksilver 6C33B monos.
We got together last Saturday so that he could get my impressions of them, I have to say they won me over. Enough power to do the job, terrific bass weight / extension / fullness, a great treble, and for him, the most important characteristic, a sweet, musical midband. To my ears, they offered the unique combination of what we seek in the EL34 tubes - midrange, with what the larger tubes provide - bass, with seemingly no tradeoffs. The blend of just enough richness, body, and liquidity with clarity and openness is a rare find. Not really sure of another amplifier at $5800 that bests them. You may have preference for a different flavor, but that would be just that, different, not better.
We're getting together soon to listen to them side by side with my Jadis and AtmaSphere amps - definitely a murderer's row of amplification. I'm sure it'll be another fun day.
By the way, AtmaSphere is not an OTL guy, he is THE OTL guy - Ralph Karsten, owner of AtmaSphere.