Consider this:
1
You do it yourself, successfully, with no problems.
But the belt has a fault, and after two weeks you have a very expensive repair to carry out.
2
You get the dealer to do it, for a fixed price, but not cheap. Any stripped bolt will be their problem.
The belt has a fault, and after two weeks the dealer will have to rebuild your engine, free of charge for you.
This is a consideration I will do during the next 10 k miles. That's when it's time to change the belt, although it's a diesel, and a straight six.
Someone around here had that problem, but with a non-OEM belt. He got the cost of the belt back.
Is it possible to check the belt thoroughly enough to know it won't fail?