Jim,
I have yet to run into a situation where my 18 is not sufficient, and excellent. I've cooked Q for 60, ribs for 20, and never missed a beat. Sure, the bigger is better is a strong psychological power, but it's simply not true always. If 18's weren't big enough then why were they sufficient for nearly all circumstances before the 22 was produced? I'll take my 18, its efficiency, portability, excellence, etc. all day, feed any crowd that comes my way, and pocket the savings. Catch one on sale from someone getting rid of one and all is the better. Just my 2 cents.