MK-VII Who's your Daddy!!!
To answer your question specifically, The MK-VII is a very reputable horn. They have maintained their value over the years and there is still a market for them. Alot of Pro's have them as their primary Alto. If you've noticed, I'm sure we can we agree that the new horns are generally bulky compared to the old horns. My personal belief has always been that the conception of the MK-VII was solely responsible for the birth of the "Bulky." Selmer is usually the leader in INNOVATION and the other companies are real quick to jump on the Bandwagon. The MK-VII had all kinds of new stuff. Fatter spatula keys, the curve at the top of the side high-E, fatter low C and D# at a slight angle, etc. All for easier access and comfort and all standard on every horn since. Not to mention that before the MK-VII, the high F# was an optional feature, also now standard. There are some exceptions to all of this however, but what I'm trying to get at is that all in all, I believe that the difference between vintage horn and modern horn is the MK-VII. Never owned one, but back in the day when High Schools had loaner instruments, they just happened to have one with my name on it for the 9th grade and part of the 10th. I really got a chance to check out this horn. It played well, sounded great and I never once had a problem with it. As far as WEIGHT goes, it didn't matter. It was lighter than the Bari Sax I played in 7th and 8th grade. The MK-VII isn't going to be any "bigger" than any of it's counterparts. In order for your horn to be a Bb, it has to be a certain size. That's just the way it is. All of the new horns are a bit heavier because of and starting with the MK-VII. If I remember right, they are of ribbed construction instead of post, adding to the DURABILITY factor. (One isn't better than the other, just different qualities, mostly sound). The only other horn that stands out for me in really close COMPARISON would be the 62 series Yamaha, the other A-list new horn for that time period. The REPUTATION for the MK-VII was already etched in stone in 1936. You can't just show up one day and kick Daddy and Grandpa off the stage permanently and expect a warm welcome. If they came out with the Ref-54 or 36 back then instead of the MK-VII, they probably would have endured the same bad rap instead of enjoying the huge success they do today. In my opinion, the only reason why the MK-VII was doomed from the start is because of who it's Daddy is. It's doesn't go well when you send Junior out there to fill the biggest shoes of all time, thus putting Pops out to pasture. Regardless of what Junior's got going on. So due to this, any kind of research that you do on this particular model horn should be limited to manufacturer specs and hands-on analysis. How YOU personally rate this horn is the way to go here. It does however, look like you did everything right in going about getting this horn. You scored a Professional-level Selmer tenor at a good price that stacks up well with any Pro-level tenor out there, past or present. On a scale of 1-10 in the Professional Class, I would give the MK-VII somewhere between a 6-9 in general with a good set-up and a great mouthpiece. You got the set-up. Now go for the best piece sparing no expense and you'll be good to go.
Happy playing, jb