@martin: I seriously doubt the IR detector used in the new design is laser based. That'd be extreme over kill. In fact, I've never heard of an IR laser in a slot detector because a simple IR LED and phototransistor work so well without the added expense of a laser diode.
If you know the actual mfg part number, and it proves to be LASER based, I'd love to learn of the new technology.
ps: the ball will stick if filament dust builds up on the floor of the housing. Bearings don't like to roll over obstacles, and the Bondtech gear likes to create chunks of filament dust if the nozzle is being temperamental. But this all will depend on the spring force applied to it. My kit is in the mail, so I'll know soon enough.