Back in the late 70's we installed Onduline roofing on our huge barn. The colors faded or flaked off very quickly. We sold that farm in 1991 and the roof was still going strong. The present owner is a golf course/country club. They still have the same roof, and it has never been painted since. This is 2012. That makes some 30+ years. This is in Lancaster NY which is just East of Buffalo, and is one of the heavy 'lake effect' snow locations in this country.
Ondura is virtually the same product (possibly the same I don't know for sure) We did use their proprietary Onduline fasteners. Most of the pitches are 6/12 or greater. The old ceder shingle roof had lasted nearly 40 years, but had to be removed. The Onduline was fastened directly to the original wooden planking which was in excellent condition.
The only part of the barn that did not receive the Onduline roofing was the barrel roof section which is not conducive to anything but roll roofing.
If anyone would like a photo of the barn, please email me privately
While I'm sure steel roofing will last longer, the Onduline was and is a good second, and a whole lot less expensive. :thumbsup: