I'd like to thank everyone for chiming in, and it's time to give some impressions on this setup!
First, the Feisol CB-40D is great. It holds steady at literally any angle. The screws get tight but the adjustments are still smooth. The friction knob is impossible to use, however. It's shallow and has a very stiff movement past "half tight" which is extremely difficult to crank backwards. I leave it set around halfway which allows enough freedom of movement yet doesn't let the camera fall down. Feisol's QR plate has offset safety slots in the bottom, so you can slide the camera forward if you mount a teleconverter or grip to recenter the weight.
There's a couple small things I love in the Feisol which the Gitzo G1278M does badly. One is the Feisol's QR plate actually gets tight. The Gitzo's just isn't grippy and there's a spring pin which sticks up and that makes it hard to begin threading the plate into a camera/lens collar. It simply doesn't stay where you put it. Also, the Gitzo is about 1" taller but it's heavier--yet the ball diameter is smaller than the Feisol. I do prefer the Gitzo's lever cranks when gloves are used, however. I find the Gitzo's ball lock knob offers a finer amount of adjustment.
Second, I purchased a GS2320K Ground Level Kit used from B&H. The kit includes the following, L to R:
Allen wrench for set screws to lock tripod head to mounting disc, safety screw/weight hook, dual-threaded head disc screw, Safe Lock head disc...
It assembles like so: Dual-threaded screw goes into the disc, weight hook threads into the bottom...
Now why is this useful? One, most tripods have a center column. This is a problem with the legs splayed wide if you want to keep the camera low to the ground. Only two legs are touching the floor! Also, lowering the center column when inverted still poses the same instability issue as when extended upwards.
Problem solved!
It can also be flipped over to get the camera super close to the ground (imagine this is an FA* 200 macro instead!
)
I could throw together a video review of the Feisol head is anyone would find it useful.