I have a G50, and while I can't comment on how the ergonomics would be for you, I have some information that might be relevant.
It is rather shorter and stockier than most 4/4 cc's, because it was designed in part by Chuck Daellenbach of the Canadian Brass, who, from what I understand, is not a very tall guy.
This might lead one to believe that it would be better ergonomically for shorter people.
I am not short, but this hasn't caused any problems for me, other than having to rest the tuba on my legs rather than the chair as I did with my previous tuba, a PT1. A tuba stand would also make this problem irrelevant.
Overall, I am very pleased with my G50. When I was trying LOTS of tubas to find one to buy, I found it to be more rich in resonance than any other, and it seemed to project more and fill up a room better because of it. It is perfect for me, a college student, because it is very versatile. As you might expect, it works well in quintet, and really can hold its own in orchestra (although someday I will get one of those BAT's, maybe a MW 2265 or PT6... oh well, that's a long way off!)
Anyway, I recommend it - it's a good horn, and the ergonomics have worked out well for me, though you will have to try it yourself to find out!

Good luck in your search!