I can understand wanting a tire liner to use with cheaper tires to get the same protection against flats as more expensive ones, but it seems to me that you'd be taking a double hit on rolling resistance and ride quality. Once from the cheaper tire and again for the liner itself.

The other thing that keeps crossing my mind, when someone says they've only had X flats in Y years with liners, while I don't doubt them how do you know that it's the liners that deserve credit? I've had fewer and fewer flats as I've moved away from flat-resistant tires. I basically have rare to no flats now, and it's not a consideration in my tire selection, so I have to believe that the change is due to other factors. I always wonder if someone removed his tire liners, if he might still have fewer flats.