cjmchch:
I come back to what I said earlier - is the speed at which you are going to watch your program going to be different if you are on a 100Mbit data pack than it would if you were on 100Mbit unlimited. It will be identical! Your PERFORMANCE will not change at any given point no matter what plan you're on.
I think it's reasonable to expect usage-based billing to give better experience than unmetered.