I just found this thread.
To Threadstarter - there is another discussion on this topic that followed at length from my short review of the Sirui (which also includes my follow up report on its usage in my travels).
http://www.clubsnap.com/forums/showthread.php?t=686089
I would strongly suggest that you
conduct the tests -
(a) Ball head Test - Test your combo lens and camera with the tripod and head in the shop for at least 20mins to make sure it can do the job. Put the camera and lens (you expect to use) on the head and tripod and shoot at f22 with a polariser and shoot at an object at least 15 feet away at ISO100. The long exposure will show up whether the whole set up is stable and whether there was creep OR Tripod wobble.
(b) Tripod leg stability Test -Open out the tripod legs to its maximum extension and press down on the top of the tripod with your left hand and at the same time, use your right hand to hold the middle of one leg and try to move it back and forth. Even though the tripod may be carbon fibre (one of the most rigid materials), poor quality tripods tend to have a lot more movement which is amplified by the poor construction of the joints. Clearly such movement is impossible to erradicate completely but the better made tripods control this problem far better. The SIRUI was a complete surprise in how rigid it was - always remembering that its a small travel tripod, the volume of movement is the key.
Gitzo is a great brand but the super light travel tripod is a compromise. All light tripods need to be a compromise.
I had wanted the Gitzo myself but went with the Sirui in the end for very practical reasons.
1. If I find myself not carrying a tripod around, then my investment cost is much lesser.
2. It has to be light and small enough to be actually carried around without being a pain. A major problem is that if its too big it will not be carried or used. If its too small it will not be stable.
3. It has to be able to do the work I want it to do - shooting landscape with long exposure. Stable enough to execute this with the gear I travel with.
4. Be actually used, abused in really tough conditions like desert, rain, rock mud and water conditions. (I would have a lot of difficulty in using a $1k tripod in such conditions). BTW being in Arizona a lot of fine dust got into my tripod and it got gritty. I managed to remove it all later when I cleaned it up. But I also felt glad that it was not a Gitzo that had to suffer that kind of conditions.
Good luck on your hunt for your perfect tripod system.
Cheers