When restoring a new roof with Topps you are cooling the building, stopping the leaks and probably the biggest advantage over new metal is the cost and the tax benefits.
You should always check with your accountant but we have heard that you should be able to expense everything you do with Topps in the same year. With a new roof it would be a capital expense and would have to be amortized for close to 30 years. You would get a leak free warranty with Topps for either 5 years or 10 years (depends upon the system purchased).
With new metal there is no leak free warranty or at the most 1 year. There is no down time with the Topps System.
At the end of the 5 or 10 year, a simple power wash cleaning and application of a fresh Topps Seal coat extends the warranty. This system is long term and only adds minimum weight to the roof.