I recently had a chance to play a reference 54 and a Series III next to my old (beat up) '55 Mark VI and the Mark VI just has this certain sound, big broad but mellow around the edges, but still can be pushed to a brighter sound. Just more flexible....I like to get a big breathy tone a lot of the time and it is just more available on my Mark VI. But, I've also been playing that horn for about 5 years and liked it more for than the '68 Mark VI I sold to get it. It has a more complex tonal range than the '68. I also just tried out a '51 SBA that had a really sweet tone, but didn't have the flexibility of the VI...couldn't push it past the sweet tone to a more powerful sound as easily (not the John Coltrane any trouble with his). This is all a lot of fun and there is something about the Mark VI, especially the earlier ones, that is special, but I can't believe people are shelling out the insane prices on these horns they are, even on eBay with no trial period. I prersonally wouldn't do it. That SBA I just tried out came from a dealer who swore it was all original, but it was clearly a relacquer...just because the lacquer is dark, doesn't make it original. Fortunately, I had a trial period on it. Oh...back to my point. It's fun to get into the old obsessive compulsive disorder about getting just the right horn, a piece of history, etc. but I think it still comes down to the player first, then the combination of the reed, mouthpiece and horn is probably the last 15%. Lots of great players sound like themselves on whatever they play. There are so many nicely made new saxes available. For the prices people are paying for Mark VIs, you could get two of a lot of pro model new horns so you have one as a back up or you could get two voices (soprano and tenor). The difference in the sound of the horns I've played over the years has been so subtle most of the time, that subtletly is often immediately lost as soon as you play in most live situations. And in a studio, you can do so many things with the mic and mixer. Another thing that the Mark VI had is number 3 in th post above...look at how many great players play (and played on) a Mark VI. If you really look at, what other horn was even worth playing through much of the 60s and 70s. Conn and King were no longer offering anything competitive. What else was out there that was even comparable. SML? Buffet? Whatever you do, it doesn't matter what sax you have in your hands as long as YOU can make it do what you want it to... Most importantly, have fun! Jason