[daltore]

Ultrasonic rangefinders can cause interference, but only to other ultrasonic sensors. It comes with the territory, and it's a risk you assume when you use them, which is why they've been legal in the past. There's no way for them to interfere with any of the new control system parts either, so there shouldn't be a reason you can't use them. In coming years, possibly, to encourage pseudo stereo vision (camera ticking back and forth between two positions), but other than that, they'll probably remain legal.