Due to inadequate oven capacity, I roasted two 14# turkeys for Thanksgiving on the gas grill for the first time on our apartment balcony here in Singapore. First I brined the turkeys for 14 hours. They were both done to perfection 2 180F in about three hours at 350F. You can google info on roasting and brining turkeys. I can't find the bags in Singapore but brought some from the U.S.
I've been using the Reynolds Turkey Size Oven Bags in a conventional oven since their inception and would never even consider using another method. The turkey may not be quite as brown as other methods, but it is always succulent and juicy, nothing but compliments from guests. To me, the idea is to have a tasty bird, not a dried out, pretty, browned one.