I run into so many clients that assume that sheet metal roofing will add an a lot more to the roof trusses. This is not true, it is actually a small portion of the weight of asphalt shingles.
I also hear client’s concern about the noise, and no it is not the old tin roof noisy rain. This came about primarily in the 50’s when the old style tin double-lock roofing panels were installed over beams or 1 bys with no sheathing or insulation to reduce the noise. So no, you probably won’t be singing rain on a tin roof.