All I have is the small 110 HF flux core so I can't speak to anything else. I did have a certified welder help me with a new nut inside my oil pan and he gave me some good pointers for using it.
Since they tend to be 'dirty' by nature take the time to brush and clean each spot weld as you go or before hitting that area again.
I watched as he went about doing my oil pan and it was spot, peen, wire brush, and move to another area or wait for the heat to abate, then it began again.
So far that's worked for me with my panel repairs just fine.
