I think you might not be looking at the best line for your use case; the Salsa Airs are extremely lightweight. There will always be a trade off of weight for durability, with the Salsa Air and Topas at the two extremes. You need to decide where you are on that spectrum. Personally, I would not go for a metal suitcase. I'm too afraid of one bad drop denting it where plastic or fabric would have conformed.