It's a good point, whatever you have been playing on will feel familiar and comfortable, something may actually be ergonomically better, but if it isn't what you're used to then it will feel odd or uncomfortable until you get used to it.
I agree with you that the RH side keys are generally higher up than they need to be on the majority of modern horns.
I recently tried a T902 myself and loved it, the best tenor I've ever played, I was equally impressed with another T902 I played a week earlier though on spent 5 minutes with that one so didn't make any solid opinions at that time.
What I believe to be the case is that (good quality) modern horns, e.g the T902 are closer and more consistent with intonation (as a general rule of thumb, many vintage horns are solid in these areas as well), They are generally slightly brighter but the tone is more consistent throughout the range. I find that many vintage horns have fabulous bottom octaves or really sing in the top register but can't carry it all the way through all the registers. I believe most modern horns are more consistent throughout the registers but therefore not necessarily as good in particular registers.
I also think many modern horns are less resistive to blow and aren't as mouthpiece choosey. In saying that, I like a bit of resistance and my Martin Handcraft alto is very nice to whatever I stick on the end, metal or other.
I own a Hanson SA-8 alto. as far as the alto models go, the Martin wins overall. The ergonomics aren't as good on the Martin and it doesn't run as slick unless set-up very well. The Hanson has a crystal clear projection and a very large rich sound. I find it slightly too much and it cuts through very well making it seem fairly bright (to my ears). I think it would be great in a live situation or with electrified bands. (I don't find it too bright in a live situation, I could do with some more edge actually so I normally crack out the metal Link for live use as it's brighter and louder than the tone edge I normally use). The Martin on the other hand has a very very smooth and sweet sound that is what most people would describe as lyrical I guess. It still cuts through and can roar like any other, but the Hanson can't touch it on the ballads and quieter more homogeneous playing.
I would assume the same basic principles apply to the tenors, though I haven't managed to play a Hanson tenor as of yet. I'm upgrading my tenor sax and I've narrowed it down to the T902, the Hanson or a vintage horn if I can find a good enough one when I have the money to buy. my vintage horns of choice would certainly start with a The Martin and a Conn 10M along with some others.
Hope it gives you a bit more of an idea about the horn(s).