Just realized that I didn't fully answer your question, Fly...
8100 or so BTU per pound in pellets.
My stove is around 70% efficient, so I get a little over 5,600 BTU per pound of pellets burned. My Castle isn't the most efficient stove out there, but it's simple, reliable, is easy to clean, and looks good.
Some of the pellet stoves get as much as 86% efficient, I think, but the more efficient stoves tend to be a lot more complex and a lot more expensive.