I'm certainly not bashing anyone here or anyone's decisions on rubber roof issues, but I am totally of the opinion any rubber roof is a disaster waiting to happen regardless of age. My rubber roof membrane started failing after 5 1/2 years service, I full time. Now if you are a weekend camper and your rig sits under a roof most of the time I guess rubber might be ok, but for me NO MORE RUBBER ROOF EVER.
I had mine replaced with RV Flex Armor, rvroof.com, and the difference is amazing. Obviously no more leaks through the membrane, but the sound silencing is amazing as well. I can actually hear my television when it is raining. My RV Flex Armor was installed in January 2016 and this is my first summer with it. I host in Panama City, FL and the difference in how my a/c's work is amazing as well. The RV Flex Armor coating is 3/16" thick and the extra insulation allows my a/c's to actually cycle on/off during the hot summer afternoons in direct sunlight and 90 degrees.
If I were going to buy a new RV right now, which I'm not, I would have the RV Flex Armor installed before I ever moved in and would consider this extra cost just part of the price of a new rig. Yes, I would spray over a brand new rubber roof and all of the caulking required to keep it from leaking.
I do not work for or have any interest in RV Flex Armor other than being a completely satisfied customer.