Roughly 25% of the posts on the Prius group are about how to turn the beep off.
Having driven both, I think you're confused. The Prius' with which I'm familiar beep CONTINUOUSLY when in Reverse. This is irritating, at best.
**The OP, I believe, requests a single "beep" or chime when the gear is changed from one direction to the other.**
Having experienced this problem more than once with our MS's, I have to concur; brilliant solution. This, or something similar, is needed as sometimes the car simply does not shift into the expected gear thus leading to unwanted surprises when maneuvering.
Bravo for suggesting and I hope TM will incorporate ASAP.
p.s. Also, from above, this is the crux of the matter--it's the "failure to comply with my command" that is at the core of this problem. If I think I'm in gear "X" but am actually in the opposite gear, that's when problems arise.... Trust me, once you've driving an MS long enough, this is very likely to happen to you at some point. (Hence, why I wish EVERY Tesla engineer was assigned a car upon hiring; there's a lot of stuff that would be designed out/corrected if Tesla's staff actually lived with these cars every day.)
I FULLY CONCUR with this from above:
"
Actually it would be helpful to have 2 different sounds:
one to tell you when you've successfully changed gears and a different sound that tells you when you've moved the shifter without the car changing gears"