I will say this...the design of the GT3542XLS is wonderful. I have not had the pleasure of trying out the RRS tripod in person, so it may be a bit above this tripod. But...WOW. This thing is ROCK-SOLID. I locked down the Jobu, started recording video, then stomped around on my deck (which is getting a little rickety). The camera hardly registered any vibration at all, where as my old tripod usually registered a ton.
I can't imagine needing extra height with my Jobu attached to this thing, and the Jobu is very similar in design and dimensions to the Wymberly and Mongoose. I'd suspect you would have around 68" of total height, and around a 65" eye height with a camera attached to any one of those tripods, which is just about perfect for a 6' person. I figure I'll need some additional height for landscape photography, especially if I need to drop a leg down a slope or something for better leveling. Given the stability of the GT3542XLS at full extension, I am not worried about using a center pole base to give me the extra height I need. With the wide angle lenses I use for landscapes, the tiny amount of vibration that might actually reach the camera shouldn't be an issue (especially with a camera with a less-dense sensor than the 7D.)
So, for those of you who are wondering about what tripod to get next, and are interested in Gitzo Systematic...I'd say only consider the XLS if you are nearly 7' tall!!! I can't imagine any other reason someone would buy this thing for general purpose use. If you really need the "overhead" capability, then it will serve that need superbly well. The base was about a foot over my head when fully extended, and with the Jobu attached, the camera was nearly 2 feet over my head. For all other circumstances, the GT3532LS or GT3542LS will probably serve you well. I had a little bit of a hard time with the four leg sections on the XLS, and not just because the legs were so long. I've ordered the GT3532LS as the replacement instead, as I think the fewer leg sections will be easier to work with.
Well, hope that information helps other prospective buyers out. If you are a giant, get the XLS. If not, get one of the other Systematics. If you got the cash, the RRS sounds pretty awesome, but I would have to actually test one out side-by-side with my Gitzo to really feel out any real-world differences. I wouldn't be hanging from the tripod myself, either...and I suspect the differences are minor.