I happen to like the angle of the lead pipe on these horns. I have a 6/4 Nirschl and initially, it did take some getting used to, but now that I have been playing it for some time, most other horns don't feel as comfortable to me. I feel the valves are in the perfect place for my right hand to comfortably reach, and it has a some very obvious also comfortable spots for the left hand.
To me (and I think this works with every tuba ever made), the trick is to sit up comfortably straight, not tense/hyper-extended though, and bring the horn to your face. Not leaning in or hunching in to the horn. In the beginning, it took some leg contorting to have it feel like it wasn't going to fall. Now that position is natural. My left leg tends to be a little more forward and my right leg actually supports most of the weight of the horn and tends to jut out to the right a little. I do use a tuba stand for very long rehearsals, but I prefer playing without one.
After looking through the pictures on that site, I'm actually on there. There's me.
http://lh6.ggpht.com/_VxWph4lhM8A/S2TNV ... 821%29.jpg" target="_blank" target="_blank
To me, I look upright and comfortable, my legs are in the position I tried to describe, but a picture's worth a thousand words.
This lead pipe design comes from the Chicago Yorks, and the players (Arnold Jacobs and Gene Pokorny) who got to/get to play them don't seem to have any trouble. The accurate copies of those tubas (Nirschl's and Yamayork YCB 826's) for me play better than Hirshbrunner HB-50's and Meinl-Weston 2165's with the "fixed" leadpipes.
YMMV, but I think that we are all different shapes and sizes, with different preferences and I think it's great to have many different choices. I don't think it needs to be fixed, just maybe isn't a match for you. A possible solution might be to offer it both ways to satisfy both preferences, but it would most likely be too costly to make one model 2 ways.
Well that was a much longer rambling than I originally planned, I hope this post helped someone in someway.