Good summation up yonder, Whistle Stop. I started out on steel strings, then shifted to a classic guitar early on. I'm used to the two-inch fingerboard, and although I can play a steel-string guitar without any difficulty, it always feels like I'm trying to play on a toothpick. But I suppose in time I could get used to it if need be. I've never used my left thumb to fret a string. I've never run into an occasion where I felt I needed to. But then, I can manipulate full bars with ease, so. . . .I feel that classic technique is the most efficient way of playing a guitar, at least ergonomically, but the ultimate test, of course, is whatever works.
Don Firth