How does my MF A308 compare to modern integrated amps in the $3000-$6000 range?

I also have ATCs; SCM11v2s.

I also really liked the MF/ATC matchup, but the Luxman is even better.

But only you can decide if you want to try something different.

I like to buy used (here or other sites). That way I can try gear for myself and flip it back at little/no loss if I don't like it.  

Just my 2cents worth.

I went from a Musical Fidelity A5 integrated (which I absolutely loved for years and years), to a Luxman L-509X - and it was a definite upgrade.

I got the Luxman used for just over $6K and thought it was worth the coin.

Improved sonic textures and tonality, more features and those meters! :-)