I did the 3M with the drill bit, it was pretty easy especially if you have a cordless drill. I kept the light covers on and put 3 layers of masking tape on the paint around them and had no problem. BUT still be careful not to touch the paint. That’s about the only thing you can screw up.
My car is parked outside 100% of the time either on the street at home or an above ground lot at work. The re-do started to get slightly hazy after about 18 months, but when I sold it it still looked good after 2.5 years. Even if it starts to fail, I would argue that once you’ve done it once and see how easy it is, you’ll have no reluctance to do it again if need be. Its really no big deal, just read the instructions beforehand and follow them exactly as you go through. Easy Peasy Sunday morning project.
I also thought about replacing the covers, but when I saw the price tag of a few hundred dollars each versus less than $20 and an hour of time, it was a no brainer for me. Even if you screw it up somehow(?), you can always buy new covers later.
I’m not so sure about the concern re: taking the “protective coating” off. It seems to me the coating has failed anyway, my covers were opaque and looked like crap. What is the “protective coating” protecting at that point?
I did it for appearance, but I did find that night illumination was quite better. The headlamp beams were not as diffused as before.