i've tried it
in all my trials and tribulations i have tried the roof reviver system. first off, the people there are absoultely wonderful to work with and they will help you market your business using their website and downloadable video. with roof reviver you have to spray the roof with their product and let it work on the shingles for about 20 minutes. then you rewet to activate the product and you then rinse off the product. the downside to this is that it takes a few hundred pounds of pressure and you have to rinse every inch of that roof. if i did a 2kft roof in 5 hrs i would have been tickled. so i tried the product named cpr (cleans porch and roof). same results. i also tried the newagain roof cleaner. newagain gave me the best results because i only need about 75 to 100 psi to remove. but, i still had to rinse every square inch of the roof. newagain also does not like aluminum gutter covers. after i cleaned the roof i spent the next 12 hrs sanding down the covers and repainting them. i guess i'm saying all this to get to the point. you just cannot beat shc. i know. i have tried. shc also has it's p's and q's but in the long run it's the best and cheapest product out there to get the job done. i'm not bashing any of the products mentioned above but just warning you that if you choose that route then make sure you price accordingly.
good luck all,
rando