I had the same dilemma as you and went with the 26". It gets used as a secondary grill to a Primo XL. It works great for my needs, as we have a lot of summer get togethers with 25 plus people.
The disadvantages to the 26 are that it goes through alot of fuel, the lid could be heavy for some people and the leg joints are pretty weak, be Very gentle when moving it. If you don't do big parties, the 22" will probably be plenty, especially since you have other cookers. No matter which one you choose, I would go with a OTG over the silver.
By the way, why are you getting rid of the Primo?