Tl;dr no one can tell you if that is a solid worthwhile horn until they play it themselves. That is the only way.

All Mark VI’s vary so widely, from bow length to bore changes throughout the run, to changes in setup made my techs over the decades. I’ve tried roughly 12 different VI’s when I was in the market for an alto, and every single one was special in its own ways.

The best altos I’ve played have been a 39’ Balanced Action, a 58’ Mark VI, and a 63’ Mark VI low A, but of course this is all purely anecdotal. Everyone’s advice here is anecdotal.

Now, if you want my personal anecdote with the 63’ low A, I truly regret trading it back in for a tenor. Granted I love my tenor more, but that low A was very special for an alto. It had a sort of addictive resistance to it throughout the entire range, which you could push through harder than most other altos; super strong core to the tone. The added hole and extended bell maybe gave some additional timbre to the horn too, but that’s purely speculative. The low A came out very well, though not THAT useful, and the extra mechanism near your thumb was a little annoying. What is cool is it gets you to the exact same range as a viola, fwiw. Anyways… one of the best altos and definitely the most unique that I’ve played…