I thought they already said, weight is the factor?
His point was, you can't just 'register a drone' if it's racer, as every component and setup will be different depending on the pilot...
The only way it can be done realistically is if you register a set of components and then update those components if you change things.....other than that you just register the fact it's say an x-shaped 220size quad copter...then the weight.