Hi, it is funny that I am going through the same..
Thanks for the excellent notice about shooting when sitting on the ground. I thought I will order GT3532LS, but now I think the 4section is more usable. Just one doubt I still have: the lowest section of the gt3542LS leg is only 20-19mm vs 23-21 by gt3532s, will it be enough? The 4section legs of the gt3542LS have visibly more flex than those of the gt3532s. Can anybody assure me, that this is not an issue? My biggest lens is 70-200mm on the Nikon D800 body, maybe later I will add 400mm. No plans for anything bigger. And I am choosing between Acratech GV2 and Arca Swiss Z1, I like the GV2 very much!