1. They are heavier than shingled roofs. The reality is that on average steel roofs are approximately half the weight (100 lbs per 100²ft versus 240 lbs per 100²ft).
2. They will attract lightning. They are no more susceptible to a lightning strike than a conventional shingled roof. Of course, steel roofs do not burn.
3. They are more expensive than a shingled roof. While it is true that the initial output of a metal roof is more, you will save money with less maintenance and added longevity.
4. They are loud when it rains. This is not true. What we forget is that there is a ceiling, insulation, a roof deck, synthetic underlay and then steel panels. It is not like sitting in a tin can. You do not hear the rain any more than you can on any other type of roof.