I've read that the Frigidaire 1/2 HP has a plastic casing. How durable is this casing, and does it offer adequate protection and longevity?

Most standard garbage disposals opt for plastic casings because of how lightweight and cost-effective they are. The Frigidaire 1/2 HP is relatively durable for its price. In fact, its casing feels better than most other models in the same range. If you really want durability, however, InSinkErator is better than most.