You should only use metal roof tiles,in high fire risk areas.

when anyone walks on them they dent.

includes

painters

cable guys

etc

Are you talking about standing-seam metal roofs? I've never heard of metal roof tiles.

Standing-seam metal roofs are great, and they last forever, but they are more expensive (costs for each vary widely by region. You have to get prices locally.

Heating and cooling variance is more a function of the roof's color and heat gain (but in WI, I doubt there would be much to worry about).

I grew up in South & metal roofs were for shanties & outhouses. However, they've become sort of a fad today in some areas. Our house was built w/ cedar shake roof, one of worst roofing mat'l choices ever. By the time it was 20-y.o., it was shot betw. sun damage & crows cracking nuts on shingles. When we decided to reroof, I did a lot of research, including metal. I talked to our fire chief. He said firemen hate steel roofs. If there's fire in attic, they get shredded when they have to rip it off to get to source. We went w/ lightweight concrete tiles, which I love. One caveat re metal. A lot of roofers just lay it over old roof, trapping dried out shake & its embedded bug population. Our contractor demo'd roof down to rafters, resheeted w/ plywood, then put on tarpaper & tile. Given wood comes from lumberyard w/ termite larvae, I had house fumigated after sheeting.