I have used one since we bought our Cougar new in 2016. We have about a 6 month season so basically we cover the Cougar for the winter, then no cover for the summer.
I'm 70 and both put the cover on and take it off by myself. The biggest problem is getting the damned thing back in the storage bag after I get it off in the spring
No problems with scratching or any other damage from the cover. I'm thinking anytime you can protect your investment from UV and the elements for months at a time it's a good thing.