We have a 2004 Itasca Sunrise. Never had a problem with our fiberglass roof until 2015. A big blast of wind tore the roof into strips. Luckily, we were in an RV campground outside Amarillo, TX. Rodfathers RV Body Shop was only three miles away. They finished removing the old fiberglass sheet, found no damage to the actual roof, and put on a new fiberglass covering.
Instead of replacing it the way Winnebago installed it, they glassed the fiberglass to the roof. It's never gonna come off, and it looks great.
I think you'll like the fiberglass. It's a lot less maintenance work than rubber, as I've learned from past experience. Just check your caulk regularly.