I usually smoke 4 at a time in my 4-rack, one on each rack, yielding about 24 pounds of cooked, pulled & bagged meat. This fits my program of a 14-18 hour cook.
I don't think I would try to put 6 butts in the 6-rack because it has the same heater bulb as the 4-rack and I'm guessing would take the cook time up to 24+. I would also guess that lower-density foods (fish, ribs, brats) would not be affected by the extra 2 racks full like 6 big hunks of cold meat.
When I tested my original 4 side-by-side with the digital 6, 4 butts each, the results were almost identical.
Kirk
