One cable to rule them all! Aftermarket cables are not cheap, even when DIY if you are using high quality materials. With all the different connections out there for SE and Balanced, it can be quite expensive to get separate cables for each device. Mini-XLR's combine a robust, compact, lightweight design, with low cost and should be a no brainer for a headphone connection. I understand Ray Samuels is an avid photographer which led him to using the Kobiconn connector, but it is only marginally smaller than a mini-XLR, it forces a right angle which can be awkward at times, has poor strain relief, limits the geometry and thickness of wires coming out of it, and is quite frankly, ugly. Saying all that, I think Ray is a very nice fellow and his amps sound fantastic so this isn't to impugn him or his work, just the connector itself. I was dissapointed to see ALO and Cypher Labs adopt this connector as well.
As for using full-sized XLR's for all the adapters, they are quite large and heavy, especially for something used portably or transportably. A number of commercial manufacturers, have offered up a system of adapters based on the mini-XLR, most recently ALO with their Green line, and it seems that people think this is the right way to go. I know my cable and adapters was a hit at a recent meet and many of the Head-fiers there will probably go down that path, too. What I would love to see eventually is the use of mini-XLR as the standard for both portables and desktop amps. I see it as the perfect middle ground (for SE just jumper or leave untouched the added pins).