I setup my new Airport Time Capsule today and decided that I would do a little test to see just how much faster wireless AC was. I know this test isn't scientific in any way and it's just a gee whiz kind of thing, but I did find it interesting. I used Black Magic Disk Speed Test to read and write to the SSD drive of my late 2012 quad core i7 Mac Mini that was plugged into the Time Capsule via Gigabit Ethernet. On the left is my late 2013 rMBP connected via 5ghz Wireless AC. On the right is my late 2012 rMBP connected via 5ghz Wireless N. Obviously I didn't run the tests at the exact same time, but they were within about 30 seconds of each other. I did the tests a few times and got roughly the same exact numbers each time. It's interesting to see that the wireless AC didn't double the results like I had expected it to.