Naw...they aren't a waste of money. They work great but your probably just doesn't like 87 octane fuel. Mine doesn't. It runs horribly on it. If you are putting on the MPG tune, that's pretty lean for your engine.
I know gas is expensive but is it so expensive that you are willing to go back to stock or run 87 octane fuel and a tune, then listen to it rattle? Tough value decision for sure.
This is just my personal view but I'd rather have a good performing truck and pay for what it needs to run good vs. going back to stock or risking damage.