From what I understand the functional advantages of a thread less fork is a stiffer setup due to increased diameters as discussed above, and secondly, the ease of changing a cockpit out when setting new bars, stem, levers, etc.

I was staunchly anti-thread less, that is, until I tried a well setup thread less cockpit on my new Lemond. The wide diameter of the bars makes for a very comfortable setup. Will I be changing all my bikes to threadless? Heck, no. Once a bike is setup, I don't feel the need to change it. However, a new, especially go-fast builds, I would consider going threadless.