[spidey]

Large breed formulas usually contain filler to bring the caloric content down without changing the volume (it's not just the size of the pellets). You can just add filler yourself if you need to (canned pumpkin, green beans, whatever), and then you'll know what your dog is getting and won't be paying for filler. If you want your dog to have supplements like glucosamine, just buy them and add them yourself, that way you know what amount and what quality your dog is getting in some kind of reliable way. There's nothing wrong with feeding large breed formulas, but they are most definitely a gimmick.