You've gotten some good advice to consider so far.

Screws can back out and washers break down leading to leaks.
Original installation may vary depending on area of practice and if roofing contractor is current and up to date on manufacturers installation guidelines.

Shingles...well nails can back out, tar strips break down and installation can vary too. Shingles are more prone to be impacted by storms. But wind driven rain can walk up a metal roof much easier than shingles and find an entry point.

Lifespan on metal is longer overall.


"The grass withers, the flower fades, But the word of our God stands forever." Isaiah 40:8

"Neither the wisest constitution nor the wisest laws will secure the liberty and happiness of a people whose manners are universally corrupt.� Samuel Adams