About a year ago I got myself a Conn 10m tenor sax, after playing a Yamaha YTS-32 for over 12 years.
The ergonomics are indeed quite different, but after trying it for 30 - 60 minutes at the shop, I was convinced that I could manage it.
Now, about a year further, I have no problems with the ergonomics. Even switching between my Conn (tenor) and my baritone (modern style key-layout) goes without problems.
The biggest difference is of course in the sound, the Conn has a HUGE sound compared to the Yamaha. Just the kind of thing I was looking for.
If you want to play clasical music (or something that sounds similar), a Conn would not be the best sound (IMHO).