We have! We set aside chips to offset our fuel wood usage, and place them in stainless steel serving trays that fit in our wood stove. That's something we picked up from Sean Dembrosky. I've experimented with them in a pit cone style as well but once the coals are raging it's a good deal of management effort to keep feeding it to prevent it turning to ash. It's difficult to come across barrels around us apparently, and I'd prefer not to buy them in while I have other options. That said, we do have feelers out for them so fingers crossed I can do some trials like that as well.

I agree that the lack of air space may cause a problem for the pyrolysis in a retort system.