i don't use gas that much anymore. if i did the biggest problem i would have is vertical welds. that's why i like the mig for that. less warpage like stuart said, but i find mig is a whole lot easier on the out of position welds. it's pretty easy for me to gas weld straight down but vertical is something else. although seems like you can get away with a little less grinding if it needs to be flat with gas. prob just my abilities, or lack thereof.