Fasteners are a critical component in a roof system and should provide extended and problem free service.
The fastener is the only component securing the sheet to the substrate, and at the very least, fasteners should have a service life equal to the expected service life of the sheeting (whether it is used for roofing, slide cladding, or flashings).
If you are using a top performing coated steel, it makes no sense to compromise on the fasteners, which are a small part of the overall cost of the roof system.