Eric, you are suggesting, for example, that a 3 Section Series 2 should handle my 500/4 as well as my GT3541LS. I think we will have to agree to disagree on this (and I strenuously disagree with that idea).
I think the best way to use an XLS (at or near eye level) is to use it with all 4 sections extended, but with at least 3-4 inches of each section retracted. That makes for far stronger leg joints than any additional flex from the bottom collar (especially when that bottom collar too benefits from 3-4 inches of leg retraction.
The principle works with any tripod, either 3 or 4 section, but only the XLS has such a surplus of length that the end result will get even close to typical eye level.
(and of course now the some of the other newer "giant" Series 4/5 variants could do the same but with diminishing returns since all the leg collars are bigger and beefier).