They weren't quite as fluffy as I was expecting, though they were nice and flaky. I don't know whether the mashed sweet potato made it denser, or if it was something I did. Either way they were pretty tasty. I'm going to make them again this week—perfect for Thanksgiving.
The recipe can be found here.
P.S. I just made them again last night. I tried making the biscuits thicker from the outset and that seemed to do the trick. They were still a bit dense but not as flat. Either way they were a definite success.