Upload & Sell: On
I do not have experience with all three ball heads, but do have a lot of experience with the Really Right Stuff BH-55. My oldest one was purchased soon after they came out, and it has given me great service in a variety of conditons. I do not use the adjustable friction too often, but rather loosen the main knob, frame my subject, and then tighten the knob. The large round knob is easy to find with out looking, and is silky smooth to use. Two fingertips can easily lock a BH-55 for most situations. There is no noticable sag in my copy of the BH-55, so my framing stays put. And it is so easy to do that I find it very fast. My style of loosen and lock may not be for everyone, but I find it works very well for me.
I also like the low profile of the BH-55, which has been made about as short as possible for this class of ball diameter. Another great feature is that the pan base lock actually locks the head down well, which is not the case with all ball heads.
You have made no mention about your lever release clamp, and I would strongly suggest you consider the RRS lever release clamps. Their lever release clamps are fast to use, and very secure. I change often between landscape and portrait and back, and it has become second nature for me to do that with the lever release with out thinking or even looking. Their latest minor change in the design has them able to securely clamp an even wider range of other brands of Arca Swiss brackets and rails.
I have used Gitzo tripods for many years, but when the TVC-33 came out, I decided it had enough features and extra stiffness that I needed to add it to what I shoot with. It really is a nice product, and if you want a leveling head some day, their verision also is very nice. The latest improvements to the Gitzo designs bring them a little closer to RRS for function, but their price now is also close. The larger leg diameters with the same or similar weight for the TVC series of tripods is key to their better performace over the Gitzos. In your case you are considering a 4 leg section TVC-34L, and that last leg section will be a lot larger in diameter than the 4th leg of a comparable Gitzo, giving you much better stiffness. I say get the TVC-34L now, and it will last you a lifetime. And by going with the RRS tripod, you will not have that nagging feeling of "what if".
I am also an engineer just like your self, and appreciate a lot of the features and function that Really Right Stuff puts in to their products, to make them in some cases work better that other products when used in real situations. And you are not going for overkill with the class of ball head and tripod you are considering. Getting a sharp image in a variety of conditions is a very important part of photography. And no matter which of the three good ball heads you decide on to start with, you can later change to another to try it, and suffer little loss if you sell one used.