Replaced a windshield half on my coach this past April. No problems at all with National Interstate. It was just a stone chip, so they asked if I would have it repaired but I said no, I wanted it replaced and have the work done at the American Coach factory. OK, they said, just have the an estimate faxed in and they would approve. And they did, to the tune of $1210.
I may have had an advantage since my coach is registered and insured in Florida, where there is no deductible for windshield repairs (statewide insurance regulation).
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL