I have to replace a garbage disposal in a rental house built in 1964. One plumber told me that the sewer pipes were such that the garbage disposal should be used minimally. The current tenant is an elderly lady who does very little cooking. Do garbage disposals differ in how much they grind up the food waste? Does it matter? Are there any models that should be avoided? Generally, I look for things at Costco, but I haven't seen any garbage disposals there lately.