At my welding/machining business most of our work was on farm equipment. Custom manufacturing and repairs. I also had contracts with the Dept. of Defense and built jacks that were used in Desert Storm. We used the Miller mig welders with .035 wire and welded steel from 16 ga. and up. Beveling the steel is needed to get proper penetration. I would look for a welder that has a 60% duty cycle or higher. Even though I had good luck with Miller, I don't think I would worry about the brand too much. Several brands are probably built at the same plant using different colors and labels on them. Welding with a larger mig welder is not different than welding with the one you have. The basic concept is still the same. Good Luck

 

I just looked at the Miller site and saw their 212 Autoset machine. If I was buying a new welder that would probably be the one. On ebay there is a Millermatic 35 for $595. I know nothing about that particular welder, but it is very similar to my Millermatic 200. The smaller number (35) is deceiving. It has plenty of power.

 

53 T., you are correct about different brand machines being built by the same companies. This is done mostly to differentiate the market/distribution system used. For example Miller makes the Miller branded machines to be distributed thru welding supply houses, and spends a lot of money marketing/advertising towards that market to try to build brand recognition and loyalty for future purchases. These are customers that buy more than 1 unit, buy branded accessories and replace frequently. Miller also makes the Hobart branded machines to be distributed thru mass market/discount channels to the hobbyist/DIYer. They do not advertise Hobart much, but leave it up to the sellers to do the promotional work. These customers tend to be more price than brand name driven, buy the smaller less expensive machines, and tend to buy only one or two machines in a lifetime. They also don't care who's branding is on the accessories they use.
I don't know it for a fact, but since the specs and layout/casing is so similar (just painted a different color) I'd bet the Eastwood machines are made by Lincoln.
IMHO Miller is trying to pull some of the hobbyist users over to their professional line with the "Autoset" feature. Since pro welders are comfortable with picking the two settings needed off a spreadsheet chart printed right on the machine and adjusting those settings to their own welding style, few pros would find that feature very useful or make a buying decision because of it. Just a marketing "gimmick" to promote when there is no other significant difference in brands, the old "new and improved" promotion the soap companies have used for many years.