Hey Ronnie ill get your back, if said welder produces a better weld with 0.6 then use it.
my opinon for what its worth is that the majority of chassis are put together with mig theres a reason for that
its easier quicker and produces good results
if you want to tig or mma then do it but dont moan to me about how long it took
I also believe that a migged chassis distort less than a tigged one
I think either westfied or caterham mig their chassis thats good enough recommendation for me
eagerly awaiting all kinds of flak
Ray