Do these grills cook just as well as a 22.5 OTG? I need something a little more portable for our camping trips plus I can use this grill at home when I need a little more grill space.

There's no real difference besides the space. I've got both an 18.5" OTS and a 22.5" OTG, and I can't really tell any difference when cooking between them. I like the OTG better because it's bigger, got the hinged grates and the removable ash pan, but it cooks just the same as the 18.5" OTS.