Here's a longer missive as to my decision process:
Well, for what it's worth, I pulled the trigger on the PMG TR344LBL. This is the 34mm upper leg, 4-section version with the leveling base. Believe me, I know that there are other extremely good brands out there, so this was not a decision I took lightly considering the amount of money involved. In the end, these were the reasons I decided to go with the PMG:
1. I like that it is made in USA (yes I know some of the others are too)
2. I like that the apex is CNC Machined T6061 Aluminum (same as RRS but some other brands have cast apexes)
3. I like the large, knurled aluminum **non-rubberized** twist locks
4. I like the 10-layer CF legs. It is not the stiffest one out there, but it's pretty high on the list, and from some real-world reviews it seemed like a good mix between stiffness, and weight/size. The upper legs are 34mm thick. I could have gone even beefier with their 42mm series, but then I'm not going to be mounting a 50cal machine-gun on it.
5. I was impressed with the way the legs attach to the apex. PMG has a unique mechanism for adjusting the stiffness of the legs at the apex such that, once set, the legs (purportedly) stay that stiffness forever, unlike some tripods that just use a bolt through a collar with some sort of nut that can (and usually does) work loose over time. It allows you to carry the tripod by one leg and not have it work it's way open as you are walking.
6. I like the "non-ratcheting" legs that can be set in three different positions. I know this is just a personal preference thing, but I really prefer non-ratcheting legs and also I prefer not having spring-loaded auto-locking mechanisms. Just less mechanical parts to wear out IMHO. The PMG leg lock system is simple, well made, and has fewer parts to wear out.
7. I like that it is the perfect height (for me at 5'10") with only the first 3 sections extended and the head and camera attached. With the fourth sections extended it goes to a whopping 71 inches. Most of the time I'll only use the first 3 sections extended, which will help with stiffness. Having the option to extend a 4th section is nice to have when you are shooting on the side of a hill or in very rocky terrain where you may need one leg extended more than the others. It seems it gives a bit more flexibility. (also the 4 section actually collapses to a couple inches shorter than their 3 section).
8. I like the included spikes that are built into the feet. With some other brands, you have to buy the spikes separate and then store them separate. These spikes are built in to the feet. Just unscrew the foot, then unscrew the spike and screw it into the bottom of the foot and Bob's your uncle.
This thing arrived yesterday. I've not had a chance yet to get out with it, but upon first inspection, it sure seems like a lot of attention to detail was paid. This thing is a tank and I'm really anxious to get out with it.