Hi Hoot - no attempting at making comparisons, I can assure you - merely saying that the first time I ever heard the alternating thumb style was from a Merle Travis record. I never realised, until I actually saw him, that he only used thumb and forefinger!

I certainly use three fingers myself when I'm playing that style. I also use three fingers when playing Gary Davis stuff - and he only used a thumb and forefinger as well.