I had occasion to visit the Phoenix area a couple days ago. Last summer, a truck threw a rock and cracked the windshield/roof of my car, and although other places said they could replace it, I wanted it done by someone with a bit more experience. Glendale, AZ has a huge Tesla repair center and that's where I went.
I learned that the car makes four miles / Kwh when it isn't loaded down with our usual plunder. Some of that may be due to reduced weight but as I've previously said, the car occasionally gets software updates and I did notice the energy usage per mile driven seemed to be better after the latest update. Hard to say whether the reduced usage on this trip was totally due to less weight or if some was due to the latest software.
I had to top off the charge in Glendale and we had occasion to visit one of the new Superchargers in Quartzsite on the return trip. When I was in Glendale and set the charger to Q-site, it informed me that four of the stalls at the 84 stall facility were out of service. We grabbed a burger before hitting the chargers and when we got there, the Tesla tech was just finishing up repair on the four stalls that were reported down. So, I got to see the .14% of the times that Superchargers were out of action. Being as how there were 80 stalls working and less than ten were being used when I was there, it didn't impact me. As it turns out, I really wouldn't have had to charge there anyways. Took on 20 Kwh in Q-site but the car still had 30 Kwh when we got home and were able to plug in to my home meter.
As an aside, I still have zero regrets on buying the X. For my uses, I wouldn't trade for any other car on the market. Unless it was a blue one with six seats instead of seven.