Heh, you guys really think the engrs didn't consider these scenarios and built in fail-safes to the code/logic? I'll bet (and no, I'm not going to experiment and get back to you!
) nothing will happen if you push either button at speed.
Here's one example of how they thought of many scenarios: if you leave the shifter in manual mode after coming to a stop and then hit "P", the lever automatically gets pushed back to the right so that when you return to the car and start it up, you're not in manual mode and can't shift into Reverse or Drive.