DBigDog,
Have been running a Stumps XL Baby for a couple years,
I use Royal Oak Lump, but cut the bigger pieces into smaller ones,
I also use a 3 foot steel rod to lightly tap the lump while in the chute, that helps it drop if it bridges.
Be careful to not push it down to hard and plug the chute.
I also use a guru with pit viper fan, attaching the alligator clip for the temperature probe to the top grate.
Seams to work well, with accurate results
Another tip,
In the fire box, on top of the grate where the lump burns,
I take that steel rod and poke the lump, cleaning out the ash from the prior cook, before lighting. Also helps when lit to drop some lump on the wood to,speed up the smoke.
Hope this helps