I have been playing around with three different brands of lump as well as KB in my WSM 22.5. I realize to be a true test, I probably should have done them all at the same time to minimize weather differences, but I will also admit that the past few weekends here have been about the same weather wise with regard to temp and evening winds. Anyways, on several different cooks recently, I used one 20# bag of Cowboy, made in Mexico from Lowe's, it was entirely gone at the end of a 14 hour cook, in fact I needed to add more of another brand to finish. On another cook I used one 10# bag of Ozark Oak, and had about 2# remaining when I was done. On a third, I used a 8.8# bag of RO lump, and had about 2# remaining when done. Of the three lumps, while the RO was slightly more expensive on a per lb basis (($0.77/#), it cost about $4.65 in fuel for the one cook based on the pounds used. Ozark was close behind, at $4.76 per cook, and Cowboy was $9.00 since I used the whole bag and then some. The ash content was real low for both Ozark and Royal Oak, medium for Cowboy, and the KB almost snuffed itself out due to the ash build up. I should also add that the temps were controlled with a Digi Q. So after this little experiment, I think I'll stick with either Ozark Oak or Royal Oak Lump, depending on where I can source it the easiest and cheapest in my local market. While I don't claim this to be a "scientific" evaluation, it was a very practical application in my mind. What are your experiences?