Can anyone tell me how useful they find the tripods with pivoting center columns? I occasionally do some full spherical panos and something like that looks like it would be particularly useful for shooting nadir shots, especially in confined areas. I've never had the opportunity to test one of these out in person, however, so I can't say if the concept is workable or gimicky. Is a horizontal column even all that stable? Do you have to counterweight it to keep the whole thing from falling over? Are the center columns long enough to get out past the support legs and make a usable nadir shot? Some insight from the people who use them would be most welcome!
I'm currently looking at several tripods, including the Manfrotto 055CXPRO4 and Induro CX 214 that have pivoting center columns and the Feisol 3442 or 3441 without. In any case I need something light that packs small and will support 7 - 8 kg. I intend to put on it an R-D16, NN3.1, 40D and Tokina 10-17. (It will also get the much heavier Canon 17-55 f/2.8, but that doesn't get used for nadir shots often if at all).
Also, when you start getting into 200mm and longer do you find the need to have a leveling base increase? I am wanting to attach the NN3 directly to the legs but wonder if an EZ-Leveler or Q3 would be necessary for those long focal lengths.