x2 hammah...
I've got Dacron on spools that's been there over 15 years. It differs from nylon in that it does not dry rot and that is a big difference. Sure, I'll put on some gloves and give it a good yank every year but in the end it winds up getting another year older. This, of course, does not hold true for mono or fluoro.
Change for peace of mind? I just bolted on a new trailer hitch. Had guys pushing each other at the metal recycle trailer to see who could get the old one. It wasn't horrible mind you but 11 years of WI winters and salt roads had taken their eventual toll and it made me nervous. I'll drive this vehicle out another 80K or better and I'd have to do it sooner or later. Rather not wait to lose my boat and all that's in it before I get 'round to it.