I have my PI running off a USB-SSD instead. It works very well, though initial set up can be a bit of a hassle.
Edit: - sorry, nevermind, I should have read the rest of the comments, there is a link below this comment (at time of writing)
Make sure you use the right adapter, I got an enclosure at first that wasn’t on the list, and it ended up not working. I switched to the recommended StarTech 2.5″ and everything worked.