I'm just not trusting this 3rd party adjuster, I'd rather the insurance company send on of their actual adjusters out.
The company may not even employ any adjusters here to send out. They may rely entirely on 3rd party IAs. Some of them are good, some are crap (same thing goes for staff adjusters across companies as well).
Aside from the gutters and paint, and the total vs repair, do the roofers and insurer agree on the number of squares (the size) and the pitch of the roof? Sounds basic but often it can be that brutally simple.
Once you get there, start with amount of roof to be repaired, then start talking costs of repair. Ask the insurer who they know (as a roofer) that would complete the job for their estimate. They can't steer you, meaning they cannot require to use a roofer they recommend, but it's a good way to call them out and review their own estimate.