Yeah, it has shanks and a curb chain, but it's very light, and works two handed. I use it alot on trails. Personally, I like to have a some curb on trail in case of a spook. The argentine snaffle is alot like a tom thumb, but I think you get more flex from the argentine. A tom thumb seems stiffer to me.
I've never been particularly fond of hackamores. I used one on a mare I had before. Once again it's the "feel" of it. They seem stiff to me. You don't get as much bend from one. But that could just be me.
Since bits are so expensive, I wish you could try them on a trail basis.
Becky
This is the one I like and use alot. It's actually an english bit. It can take two sets of reins. It's got just enough curb action that a horse with a good whoa will feel the curb if you really "have" to use it. But light for turns and two handed use.
Becky