Turns out I’m a thumb strummer. I tried
hard to master a pick but it’s just easier and much more natural using my thumb. Chord changes are smoother and it’s much easier to keep time…pick always felt clumsy. Given this would a thumb pick make sense? Should it only be used for picking or can it be used for strumming as well? Thanks
I’m not totally sure if this is what you’re looking for but I’ve been thinking of trying this thumb pick. Seems to be able to be used for thumb picking and strumming.
It took me a few tried to get the hang of a thumb pick, now it’s my constant companion. I’ve tried to use it, and also the black mountain thumb pick, to no avail. I’ve just not stuck with it as I have regular pick I use for strumming songs. Your mileage may vary. I have friends who use thumb picks for thumb picking in fingerstyle and they also use them for strumming.
I would say they are worth a try, because… why not? 
Part of the fun of guitar is experimentation, and finding out what works for you.
I always strum with my thumb on acoustic and did try thumb picks, but they weren’t for me. The main reason I use my thumb in the first place is because I prefer the tone produced for acoustics, and I’m comfortable with normal picks on my electric so there was no need.
It might be worth persevering with a pick for part of your practice routine though, even if you do prefer thumb strumming. You will get the hang of it eventually, and then it adds another string to your bow even if you don’t use it often, rather than being something you’re never able to do.
A good thumb pick is something I’ve been thinking about. I’ve got a white Dunlop plastic one (size L) that may be suitable for most people, but I find the “picking end” a bit too long which makes it uncomfortable to use (I have to keep my hand in a way that my thumb is further away from the strings while the other fingers are at their usual distance). Also, when I put it on, my thumb turns red/blue after a few minutes, and I don’t have big hands. Maybe an XL size would be better 
Some time ago I bought a set of Dunlop Nickel Silver Fingerpick Set, but man, are they clumsy! Especially the thumb pick. When I put them on (I tried them for about 10 minutes overall), my fingers felt twice as heavy and big and impossible to control. Plus, their attack on the strings is very loud.
Hi @Jby51, I think most people feel that way when they are starting out. Holding a pick is just one more thing to think about. Many times I wanted to throw my picks away, but I didn’t because I thought back then that learning guitar meant playing with a pick and I wanted to learn to play guitar. A pick gives you options you don’t have with the fingers (and vice versa, of course). That’s why 90% (99%?) of guitar players use a pick (except for some specific genres like classical, fingerstyle folk-based songs, acoustic blues, etc.).
To answer your specific question, I have used the old style thumb picks and I found they didn’t work very well for strumming. They were ok for the down strum, but the up strum never felt right. There’s no way to make adjustments in how you are holding a thumb pick, which I think is the problem.
I’ve never tried the Black Mountain picks, they may indeed work better for strumming.