Want to recommend a neutral 3rd party for a specialist roof inspection?

[Kenton H. Shepard, CMI]

...instead of a roofing contractor who has financial motivation to find problems.

Check out RCI Inc.

They're roofing consultants. Neutral 3rd parties who are bound by a code of ethics and don't do roof work, but are experts in residential and commercial roofing systems. Some are also experts in waterproofing systems (there are 3 designations). After looking over their website and reading about them I'm very impressed. Especially on an expensive roof that was a difficult call, I'd use them in a heartbeat. They have members across the country. I've seen a sample of the qualification tests... they're difficult.
In order to use the member search feature successfully you have to use the "advanced search" link.

The Roof Defect Recognition video course will have an in-depth interview with them.
Look for the course to arrive about early July. 5 months of research. Script at 140 pages and still growing. Some great footage shot already. It'll cover the 6 main steep roof residential roof-covering materials, plus safety and some other things.
Wind and Hail Damage Recognition should be available about the same time.
These two roofing courses will have attention to detail and comprehensive coverage.