Aye, I couldn't justify the TVS-34L. It sounds really cool, and I am sure the technology is very advanced. It can apparently handle more than 100 pounds of load, too. However...I won't be putting 100 pounds of load on my tripod. Hell, I probably won't ever put 50 pounds of load on it. So, despite all of its more advanced awesomeness, I really couldn't justify the nearly-double cost.
I pulled the trigger on the GT3542XLS. I figure I'll only need to use three and a half legs most of the time, which is fine...that should mean better stability. I did want the extra flexibility to drop one of the legs down the side of a hill or mountain, though, to get better stability on uneven terrain. I think it should make it easier to get my camera right up to eye level than a 57" tripod, too. Additionally, for birds in flight, where the lens is pointed up and the viewfinder tends to drop a couple inches, the option for greater height would also be there.
I saved a bundle by buying through Amazon, and only spent about $650. That is about 60% the cost of the TVS-34L, however I think it is more like 90% as good...so it feels like a great deal to me. Should arrive tomorrow, so I'm pretty excited! Will be nice to use a more stable tripod than I have for the last year (my old one, even before breaking, was never really great...it was my first tripod ever, about four years old, a rather creaky thing, and it tended to shift at the upper joint where the legs met the tripod plate.)