Karsten,
That's what I figured too - with extended column it must be less stable.
As far as load goes, I realize my question wasn't very clear.
My point was that since I intend to use light equipment, the weight of the tripod itself is becoming relevant to stability also. Since Aria + 135mm + flash is the heaviest combination I may possibly use (and far likelier situation is Aria + 35mm Distagon, or 50mm Planar which weigh even less), that means that maybe in my case it is actually better to have a heavier tripod.
By the way, I agree with you that for the most part Berlebach tripods support heavier load than say Gitzo or Bogen. Even more important is the fact that Bogen and Gitzo are made from metal and do transfer vibrations easier than probably any wooden tripod. In fact I have noticed with my hand on the leg of my Bogen tripod about 30cm from the top of the legs that I can feel the vibration from shutter. Obviously I can't quantify it, but it's felt easily. And that's with Aria. I imagine that would be an even bigger problem with heavy equipment.
Now, as far as walking goes. If you take Bogen or Gitzo at 2.8kg and add another 500g or more for the separate ballhead, you get 3.3kg extra weight you have to carry around. If you get carbon fiber, you can probably get this down to 3kg. With Berlebach, taking three models with "levelling" center column into account, we get following weights:
Berlebach 2042, 2-section legs, levelling center column, 114cm w/out extended column, 81cm folded, load capacity of 12kg, weight of 3.2kg
Berlebach 3042, 2-section legs, levelling center column, 135cm w/out extended column, 93cm folded, load capacity of 10kg, weight of 3.5kg
Berlebach 8043, 3-section legs, levelling center column, 125cm w/out extended column, 72cm folded, load capacity of 8kg, weight of 2.9kg
So, they're very similar in terms of weight, exception being difference between 8043 and 3042 - 600 grams. But 3042 is the tallest one, so that's something to consider. On the other hand, it's also the longest at 93cm folded, and for someone like me standing tall at mind-boggling meter seventy
the task of carrying such a beast on the back becomes somewhat challenging. The one thing I do like about all three though is that I suspect that I will not need separate ballhead. That's very convenient (and cheaper as well).
Also, I found out that 3032 can't use center column at all and it stands at 142cm high (indeed similar to 3042).
Your 8023 is a good one too, at 123cm w/out extended center column it's very close to 8043. Surprisingly though, weighing 100grams less, shorter by 3cm when folded it's capable of carrying 2kg more load. Beats me how is that possible. The only drawback (or advantage, depending on how you look at it) is that separate ballhead will be required.
So, at the moment I'm leaning towards 8023 or 8043 with a big MAYBE about 3042.