Great thread Rick.I was going to respond to the F remark last night on the VOW thread, but everything was slow as molasses and I wasn't able to post.
Anyway,I've been playing a full F with the thumb for a long time.Started when I had trouble learning to barre chord.Still can't very well.
Tom Paxton wrote a song called " I give you the Morning,I Give you the day" that is in F. I alternate the bass between the E and the F with my thumb for the song.
My real trials began when I started playing regularly at church.We do a lot of stuff in F and Bb so I had to learn to play in those chords. Capo to the 5th fret and and C position for the F. The Bb? You got it.Thumb-over F position.
rr