Well I'll put it this way:
My 5 year old steel body F-150 had cab corners rusting out, I sold it before it got terrible.
My brother's 5 year old F-150 had entire rocker panels rusting out not long after he got it, finally got it repaired last year.
My other F-150 steel body is going to the shop for rocker panel replacement after Christmas.
Currently I'm driving an aluminum body F-250 that's 5 years old now and has 98k miles and it's pristine. No rust or corrosion anywhere. Frame even looks new thanks to the electrostatic treatment they do to them now.
I'll never own anything except aluminum from now on.