Every time I inquire about problems and repairs (usually "what if" situations), I get very different responses from diff. SAs and stores. I think it really depends on who you deal with, and if you don't like the answer you get at one store or with one person, try another one till you like the answer. I know there are some SAs out there that take care of the problem quickly and will usually just try to replace your bag for you right away. But others are not that helpful. Last time I had a question, and I didn't like the answer, I quoted this forum and the person got the manager to help me.
2 years is what I was told for D&B. I think Coach is for the life of the bag, but that's whatever they consider the "life" to be...5-7 yrs based on the style issue from what a SA said. But again, I've heard of cases where they have fixed or given merchandise credit (coupons) for older bags too.