Tell
this guy how superior they are.
You can also do the search on how many Winnie roofs have come off, but I doubt you will. :B
Yes, some fiberglass roofs are very well made, some aren't.
You also lump TPO in with rubber - that is a very uneducated move, two completely different animals, and yes, I've had both - 2 with rubber and 3 with Brite-Tek.
Blackdiamond isn't the only one, our Brite-Tek (modified TPO) is 14+ years old now and still likes like the day it was installed.
As to the OPs question, look at the method of construction as well as the brands reputation. For our $$$ Newmar has been excellent and we've owned 3 of them. All 3 were bought new, you could count on one hand the number of issues we've had with all 3 combined.