First question, did you ruin the controller. The answer is no. If anything, you ruined the power supply, but that is also doubtful. You are talking 6 watts vs 3 watts, which is not a lot of power.
Second question, just plug and play. You said they have been doing it for a while now, so I am sure you are still fine.
After that, I think all your other questions are answered.
Must components are capable of handling sightly dynamic loads. For example, almost everything can work on a load from 130-90v that is rated for 120, 115, or 110 volts, because power in every building is different. The dangerous thing is under volting something so dramatically that it pulls way more amps then it can handle. This causes something to go up in smoke. The other thing is over volting dramatically, like running a 24v power supply on your 12v console, or taping something rated for 120v into 220v, which would also cause smoking.
Example of this: I once had a house electrican drop some power for me. I said I needed 2 120v 20 amp circuits. I didn't have my meter with me that day because I wasn't suppose to be playing with lights that day. So he drops a breakout box with a few Edison outlets on it. Well, I plug in the dimmer packs, and they started smoking right away. He had some how managed to get 220v out of Edison outlets. I told him this, he said it was impossible. Well, he metered it, disappeared, and came back. This time, I took his meter and metered both lines, 80v on each one. Disappeared again, and got it up to 115v. Needless to say, I have my meter on me at all times now.