Lots of just bad info gets posted about any subject. Especially rubber roof material.
I would contact your type roofing material mfg and ask them how to care for their product.
My '97 32' 5er has a rubber roof and no issues. I personally do a twice a year check up there just like I did my aluminum roofs. I've found much less maintenance with the rubber roof.
This is our 2nd unit with a rubber roof.
Three TCs and one TT and our first '84 5er had aluminum roof material. I would never go back to a aluminum roof.
Use the web for searching answers to any question. Many folks use Mark Polk for answers to different questions.
http://www.fmca.com/motorhome/polks-top-7/3425-polks-top-7-steps-to-maintain-a-rubber-rv-roof?tmpl=component&print=1&page=
