I had a chance to briefly "play" with one today at the RRS headquarters in San Luis Obispo, California (I was passing through on my way to San Francisco). Tripods are one of those pieces of kit that you just have to try out in person and I was curious to find out how it performed.
The bottom line is that if I didn't already have a perfectly good Gitzo 1348 AND I had $900 to spend on a tripod, this would be it. It is finely designed and crafted, as one would expect from RRS, and has that intangible feel of high quality.
Legs extend quickly and smoothly and lock positively. The height is perfect for my 5'11" height. The larger diameter tubes take a little getting used to, but seem to make it easier to get a firm grip particularly on the lower, smaller sections.
The Gitzo 1348 with 4 section legs does fold up shorter, goes taller and would probably be more versatile on slopes and other non-flat surfaces. I do like RRS's antitwist leg locks a lot better than the locks on my older Gitzo.
Obviously, the true test is to thrash one in heat, cold mud and dust. I am also curious to know how it withstands being dropped, scratched by rocks, etc.
Paul