I've really enjoyed the discussion in this thread. Paul, your remarks about the design history of Conns were fascinating. I just want to add some comments about blending in a concert band saxophone section.
I played a Conn for a year in high school, but only in the marching band, because I played clarinet in the concert band. Since then, I've accumulated a large amount of experience with concert band saxophonists, from both my own current band (an advanced amateur symphonic band) and many other bands with which we've come in contact. We host an annual community band festival, and we've also participated in the Association of Concert Bands national convention several times. I can say that Conns and their ilk are a rarity in this musical milieu. Partly this is a result of self-selection: Rascher School adherents aside, people who dig vintage American horns generally want to play jazz or blues as soloists, not symphonic band music. But it's also because most modern saxophones offer exactly what concert band performers need: predictable intonation, easily controllable dynamics, focused tone, and comfortable ergonomics.
Our alto section is currently all Selmers plus a Yamaha. In the summer, I swap my Selmer for my Yanagisawa. Thinking back about other players and horns that have come and gone, this French-Japanese emphasis has remained pretty steady. Other Selmers ... there was a Buffet too. No Conns that I can recall over 15+ years. Of course, we don't all use the same mouthpiece or reeds, but the mouthpiece spectrum is short, with traditional Selmer or Vandoren classical pieces at one end and conservative jazz pieces (e.g., Morgan, Meyer, Jody Jazz HR) at the other. No high baffles, and no metal pieces.
OP, with respect to the tone expected from you, much will depend on how ambitious your band is. Some bands have a "happy to have anyone who is willing to play" attitude, which naturally results in a somewhat casual approach to performance standards. In my experience, however, I have found that blending properly is challenging enough even with a horn and setup that facilitate it; I wouldn't want to attempt it with equipment that could serve as a partial obstacle. You must blend well not only with the other saxophones, but with any other section or instrument in the band, when a particular score demands it. Last year we performed a piece by Maslanka in which I had to play a sort of mournful solo along with a single flute. So, "Will your horn enable you to blend with one flute without overpowering it?" is not a ridiculous standard to apply.
More generally, it's essential to be able to play at pp over the full range of the horn. A booming or blaring tone can really stand out, negatively. There's another local concert band in which one of the alto players has a kind of cutting, "lead alto" jazz sound that penetrates far too much for a sax in a concert band. Many of the lines he plays end up as solos even though they weren't written as such. In the professional concert band recordings that I've heard, the sax sections tend to be a bit too submerged even for my taste. When you do hear an alto, however, the tone is always very dark. The players seem to be striving for the tone one would use to play the orchestral solo in "The Old Castle."