Yes to modern inverter designs. I don't think plasma comes in anything besides inverter, that was standard 25 years ago.
As for welders, I still rock my Miller 185 (220V 'pocket MIG'). The only time I really hit the duty cycle on that was welding feet at a time with the welder set as hot as it could go while welding a tractor bucket. Asking a little too much out of it, but it did it. Just forced me to take a few breaks. I have a couple more now, one is a little flux core only China special. Last I saw they were on sale in the jungle for under $70. It is inverter based. That inverter doesn't care what it gets for power. Stack a couple 16 gauge extension cords and run it across the back yard and weld some rusty painted metal, doing everything wrong. It lays down a very nice bead, for flux core. Inverter equipment is so nice. So much more efficient in the power transfer, which means less circuit needed to drive it. A transformer based machine that needs a 50A service can weld exactly the same with an inverter on a 30A service.
I recently picked up a cheap inverter TIG welder. I was hoping for an AC machine for aluminum, but I got a smoking deal on a DC only machine. I'm getting to really like using it. It sucks for large projects. The hot glue gun (MIG) can do so much more volume. Great when you don't have all day. But when you want to really get it nice, that TIG can do tricky projects that a MIG just can't do. There are some nice multi-process inverter machines on the market now. I am not opposed to those for the home hobby projects.