We have an EPDM (I think?) roof, 2003 Forest River TT. No problems at all. Only time it leaked was when a branch fell on it and created a 1" diameter hole... water got in before I could put Eternabond over it. I am assuming there is rot up there, but for now it works.
We are thinking about a new camper - hopefully (and I am assuming) what we have now will last 2 more seasons, until the kids are out of college. I am going to sell the camper very inexpensively, warning the new owner about the possible (well, definite) roof rot.
All these aftermarket roof products people talk about... Really, they should be applied / put on right when you buy a new camper? If you wait until you have a leak, then the roof now has moisture in it and putting a "permanent" roof on will just seal all that wonderful, rotting wetness in.
So... for about $150 a foot, a 21' TT has a roughly 19' roof, so 150x19= $2,850 dollars - $3,000 rounded up for fees and taxes. Honestly, that is hard to justify for me because my roof has not leaked in 13 years (except for outside damage), and at least two friends' campers have not leaked in almost as many years. Actually, I don't remember anyone I have talked to saying their roof leaked.
So... the aftermarket roof products will last at least 12 years? The "normal" "warranty" for a rubber roof. I would be very interested in hearing from people who had these roof products for at least 12 years - condition of roof, any leaks, etc.
I am very much interested in these aftermarket roof products for when we buy a new camper. Only that it is just like buying the extended warranty - you are spending a good chunk of money for something that may be unneeded.