I've never had an issue welding sheetmetal with my Millermatic 175. I know one of my friends welds sheetmetal with a Lincoln 250 amp machine. I could see in some ways that a big machine may not be able to be dialed down enough to do 22 ga, but, that's hasn't been an issue with some 250 amp rigs.
I would never buy a 110v machine if I had access to 220v.