Well, it's not quite that simple. All manufacturers give specs in the best possible light, especially on the lower end of the price range. I have no real preference, red or blue. Anyway, your post piqued my interest, so I dug a little deeper.
Miller gives a graph of duty cycle. You can find the duty cycle at any point in the range.
http://www.millerwelds.com/pdf/spec_sheets/DC12-58.pdf Scroll down to page 2.
Lincoln only gives us duty cycle at 2 points for 208V input.
http://www.lincolnelectric.com/assets/servicenavigator-public/lincoln3/imt10164.pdf Page 21.
Now, if we compare at those 2 points, the Lincoln wins by 5% at 200A and by 40%
at 110A.
We don't know what the Lincoln does in between. On most inverters, in that part of the range it tends to be a near straight line like the Miller.
If you want to know, ask Lincoln. I'll guarantee they know, but based on experience, they'll be reluctant to tell you.
My point is neither company gives you the best information.
I wouldn't buy either if I intended to run a lot over 170A. That's when you need to look at an industrial machine. I'd want to demo both machines before purchasing.
I didn't notice the rating on the Miller when I made my first post and frankly the Miller's spec on the low end concerns me. In general Miller, inverters run smoother, there's a lot the numbers don't tell. I'd give them both a go and get the one that best suits your needs.
