A well maintained roof is going to hold up very well no matter if it's fiberglass or TPO (non-TPO rubber is a different matter). There are two important things to keep in mind:
1) A fiberglass roof will provide better resale value down the line. Just as you are looking at it now, others will surely key in on it later when you go to sell your coach. If it doesn't add to your resale value, it would at least make it easier to sell.
2) You have to get up on the roof once a year and check all your seams. It doesn't matter what kind of roof you have, the seams will usually fail first. Both fiberglass and TPO are relatively strong and resistant to UV rays. It's the joints, penetrations and seams that work loose and let in water.