I have a hobart210, bought a year ago. First mig I have ever had and I really like it. I've done a lot of medium welding up to 1/2 inch steel ( takes 3 passes to weld 1/2 inch) but thinner stuff can do in one pass. I think the only diff. Between the 190 and the 210 is the dual voltage. I tried the 110 voltage for tin and basically went back to 220 and turned the voltage and wire speed down. The drive wheels are metal but the tightening mechanism is nylon, haven't had any tr with that yet and the feed speed seems constant. One thing-hobart advertises 16ga to 3/8 but they only includ the drive wheel for 30-35 wire. When I phoned Hobart about this they promptly sent me the wheel for 20-25 ga.
I work at a golf course doing maintenance in the summer so I end up welding a lot of different material and it has fit the bill so far. I'm in the process of buying a spool gun for it right now so I can do aluminum. We'll see how that works.
Another chap who works there and does a lot of welding has a Lincoln mig. I don't want to put Lincoln down but he basically quit using his and comes over to my shop and uses the Hobart, that has to tell you something