Yes, I'm sold on the thumbpick now. Thumbpick plus fingers is the way forward for me. I can get the pick sound (clack clack clack) and the finger sound (fwump fwump fwump) in the same song. Lightning and thunder. Clack! Fwump.
I mostly play fingers; I do like the pick sound sometimes but if I have to choose fingers OR pick for a song, I almost always go fingers. About a year ago I decided I might eventually want to play 5-string so I thought I'd start consciously practicing the floating-thumb muting technique to get ready. Well, my floating thumb doesn't like to sit still; if it's there on a string it wants to get in on the plucking action. So by last fall I was using thumb and fingers. Then I thought, why not slip a thumb pick on there? Might as well.
I tried a few different thumb picks and almost gave up. Too tight. Too loose. Too stiff, too flimsy. Finally found one that is just right. Now I can upstroke and downstroke with the thumb alone, leaving the fingers free for other pursuits. I especially like to alternate thumbpick on the thick strings (say, root and fifth) and fingers on the thin strings (maybe octave and tenth) it sounds like two distinct voices.