I was just about to post almost the very same question. This year I’ve been buying pellets at Tractor Supply, one of the cheapest around here, and last couple dozen bags were Power Pellets, produced by O’Malley Lumber, in Tappahannock, VA. Pellets are about 1-1/2 to 2” long. Stove Chow, Lignetics, Hamer and other brands I had been burning were half that, sometimes smaller, and burning hotter at slower auger setting. I have to use the #4 (out of 5) setting on my Whitfield Advantage II stove to get the same heat I got with Hamer, Stove Chow, and former Agway brands.
I recently did the annual comprehensive cleanout and had a chimney sweep clear the stack, so there’s no issue with exhaust. Damper is not showing me significant changes, outside air intake is clear. But I just filled the ash vacuum in less than a month, which is a first here. Chimney cleanout at the base of the stack also had a significant amount of fly ash (usually don’t need to open it in the winter). For last routine cleanout two days ago the burn chamber was filled with clinkers and was starting to burn pellets outside the burn chamber (to the side). But that was after burning them mostly at the #3 setting.
I’m not getting anything like a fluidized bed action in the burn chamber (like when I first bought it), the Power Pellets are just not burning as hot as usual (for this stove). But at the higher auger speed it does NOT appear to be burning dirtier than before.
There’s a chance that the higher auger speed combined with the longer pellets might be approximately the same, since I’m still burning about 1 bag/day. I’ll try some Stove Chow pellets next to check the difference.