After using all three methods, traditional, back button AF, back button AF off, I settled on the last, it has all the advantages of independent control that traditional doesn't, but not the thumb committing and tiring disadvantage of method two. I strongly recommend people play with all their settings to find out what works best for them in any particular scenario.
I shoot like private does with AF-On as AF Off, and I really like it for the same reasons he mentions.
It blows the mind of my bird shooting friends, but it works well for me. I find that I find the need to kill AF far more than I find selectively activating AF useful.