Be aware that the Gitzo has a much more convenient base place release mechanism. With the RRS you need tools, whereas the Gitzo can be done without tools. According to Neuro you can buy both the handles for the leveling base ($35 each I believe). I have the short one, without hook, but will buy the longer with hook.
The Gitzo feature of removing the platform without tools is nice, but not often required. The only reason I can see for removing the leveling base would be to use a center column (although it can decrease stability, it comes in very handy in some specific situations, like a shooting headshot portraits of people in succession, where eye level is at different heights depending on the height of each individual).
For the leveling base, RRS also has a version with an integrated clamp. I have that one, and dovetail plates on the bottom of my PG-02 gimbal and my BH-55 LR (they make one sized for the Wimberley II as well). Makes it really easy to swap out what's on the tripod.
The RRS short handle is $35, the long handle with hook is $70. Getting the base that comes with the long handle and hook adds $30 to the cost of the short handled base, so you save a whopping $5 if you buy the base with the long handle and then get the short handle separately. Either way, you'll save more on shipping if you just order both of the handles when you get the base. To swap them, you simply unscrew the handle from the base.