That's the 64 dollar question, Jim. The answer, I think, is that a free blowing horn is free blowing no matter what. Yes, we can change the mouthpiece setup for greater comfort or better access to the higher register and that might add a tiny bit of resistance. However, if I'm right about the bell and it's ability to vibrate being the key---it should be real easy for anybody to make the horn blow free and easy. A little tweaking of the mouthpiece/tuning slide would be all that's required.
Remember though, that some players like some resistance to push against. Other players with smaller lungs might not want a horn that can suck up every bit of air they give. So, there is still room for some individual preferences in a horn.
Have you ever tried a Calicchio or a Kanstul? And then tried a Besson? There is a big difference in the way a Besson feels as compared to the first two even using the same mouthpiece and the same shape of the tuning slide. Why? I think it's the bell. Jack Kanstul or John Duda could probably confirm this, but I don't think they want to give away company secrets!
