I've had Alloy gators on my Model S with 21" wheels, and can tell you about my experience.
I installed them myself, and it is time consuming. I deflated the tires a bit, one at a time, and used water with soap and a good mallet to whack them into place.
When you first get the Gators installed, they look pretty good. And they definitely provide protection. They did save one of my wheels on one occasion when I was coming out of a parking garage with a circular driveway and the Model S was just a little too big for the small turning radius and I rubbed the curb. That's the good part...
The not-so-good part is what happens when you need new tires, which for the 21" wheels is about every 25,000 miles. The tire shop I use had never seen them before. They agreed that they would just take off the gators when dismounting my old tires, and they put them in the trunk.
My original plan was to put them back on myself after the new tires. But coincidentally, the tire shop had scuffed two of my wheels with a wire brush / drill motor when pulling off the balancing weights. Frustrating. But they paid for a local mobile service to come to the house and refinish those two wheels. It looked great after the refinish, a perfect match in color (silver).
But before that refinish work was done, I also realized that the act of me putting on the gators originally had put marks on the edge of the wheels (after all, they use these serrated edge bits to grip the wheel and stay on when you pound the he!! out of them to get them in place between the tire and wheel. In addition, the original gators looked a little weathered, and I didn't want to put them back in place as-is. And there was the one wheel that rubbed the curb. That gator didn't look good at all.
I thought about buying a shiny new set of gators to put back on, but ultimately decided that I didn't want to go through the hassle of doing that and going through the installation. And having the first set of gators while driving my Model S for the first 25K miles was probably a "Training ground" for how to avoid curbs, etc.
So for the sake of keeping my wheels from getting additional installation marks on them, and avoiding the cost of buying another set of gators (not exactly cheap), I decided to go without. If I ever have an incident with a curb, now that I know about the mobile refinish service and their great work (Velvet Touch, if anyone in San Diego cares), I will just use them to keep the wheels looking nice...
That's my two cents worth....At the end of the day, I'm not sure that the "cure" is any better than the "disease" when it comes to the gators...