I am using the Smokey Joe Silver, with a 16 guage expanded metal grate over the stock charcoal grate to help catch smaller pieces of lump. I have an oversized tuna can with 16 x 3/8" holes drilled around the top of it to keep the coals from clogging the vents.
I've rotated the exhaust vent before and it didn't seem to make the fire move from one side to the other. I'd think ideally the exhaust would be in the center of the top like in the big green egg or some UDS i've seen.
WSM 18.5" (1981), WSM 18.5" (2014), Mini WSM (Smokey Joe Gold), GMG Davy Crockett, Hasty-Bake Suburban (Late 1970's), Bayou Classic 60K BTU Propane Burner, Weber OTG 22.5, PGS K40 (MHP Clone).