Gold standard. Or, it used to be. As noted, lacks anti-rotation feature of newer Gitzos.
Mine (1325, had it about 8 years I think) spit out one of the "feet" (a glued-in rubber plug/insert at the bottom of one leg) in Antartica, after about two weeks of moderate cold. It's been in plenty of colder places, New Mexico in November with 8 degrees F at 5 am, no problems. I glued it back in with superglue, been fine for 4 years now.
Supports a 600mm lens on a Wimberley gimbal just fine.
I had a Gitzo 1548 for my 600mm lens for a while, it was overkill - unless you're well over 6' tall, then the added height is welcome.
For the price, you should snap this up. If I were buying a new CF tripod today, I'd probably go with RRS, but it's a $1000 or more....