I have consistently cooked amazing briskets on my 22" wsm. I typically cook 2 at a time, and on average 18lb each on both cooking surfaces.
The wsm is tried and true, reliable and holds temperature amazingly well. I bought it because it's a set it and forget it type smoker, and very easy to manage temperature as I did not want to to have to babysit fire, and get some sleep with overnight cooks.