Anyone heard Mastersound Amps?

I have a Mastersound/Vaic 300b SE integrated amplifier and love the beautiful SET sound. Unfortunately I cannot comment on your question with any comparison to other amps other than with my set-up I love this amp except for the bass. The low end is not as extended as I would like but the midrange clarity and the depth and focus are so well done I bought the amp in spite of my reservations about the bass. I have Reference 3a MM deCapo I speakers and a Cary CD-308, MMF-7 TT with Monlithic Sound phono stage.
There is a review of an Ayon amplifier in the Jan(?) issue of TAS and for that matter check out the Ayon website as Mastersound has merged with them.

"I'd like to get opinions on people who have heard them."

I have heard the amps but to answer your question, I have no opinions on people who have heard them. I don't know these people personally but everyone who heard the amps with me seemed nice enough.