I have never been able to kick the thermal switch in my Miller 135. I run 023 wire and 75/25 gas. I will use 030 flux core if I have to take it somewhere else. I hate flux core and stick. I like to tig if I can take the part in my garage and mig if I can't, or need it done faster. Tig is good for thin material, but it is real easy to put too much heat into a piece with a tig machine.
I can do some very nice looking welds with the Miller 135 and the fact that it runs on a 20a 125v circuit makes it far more versatile than other machines. I have run it on generators and shore power with up to 125 feet of 12ga extension cord. My brother has a 252 miller that is very cool. I wish I had a bigger mig, but I make do with what I have. My tig is a 460 amp Miller as well (330 abp sine wave transformer machine that weighs 1,000 pounds), and my plasma is a miller 375 extreme that runs 125/250 v. My hood is a miller elite as well. Yep..........I like blue. My reloading presses are blue as well, and my truck is blue, my sand rail..............I am getting a little tired of the color blue, but the equipment seems to be attracted to me.
The 135 will do 1/4" material if you do your part. It is happier with 1/8 and 3/16 steel. I have done some stainless as well with tri mix gas, when my tig torch sprung a leak. The passport miller is dual voltage and might even do stick if I remember right. I could have really used that in the past. I have done a number of small fab jobs and repair jobs that were not structural and needed welded on site. I bought my 135 because it had the infinite knobs. My neighbor let me borrow a lincoln, but it had the click knobs.