I use royal oak lump or humphrys lump, you will get longer burns out of briquettes but its a gravity fed so who cares?
to me if i am going to smell something cooking for hours i love real lump, the smell along with whatever is cooking gets my vote, very little ash, and if i have some in the shoot when i am done, i just leave it in there until i start it up again, if i do that with briquettes they swell from moisture, and can jam.
i dont really have any issues with jams, from lump i used to break up bigger pieces, but now i have a bar for clearing them, i can tell if its not keeping temp to run it up and down the shoot and in 15 min all is fine.
Fire & Spice Cook Team
Backwoods Authorized Dealer
Old weber gasser
Uuni pellet fired pizza oven