I am 100% in favour of fitting the Cliffys - did so on my AFM and FH with new playfields. They'll wear just like the old one did if not eventually. In home use might take longer, however all you need is a ball drop on the edge to create a little splintering and you have the start of wear.
As for mylar, not as important, up to you. I did not on the AFM and FH, but did on BBB (which was a new field, but too risky on that particular title).
