Upload & Sell: On
Per CPS, only true reading is thru Canon
One thing with non-Canon software is you don't know if you're getting the reading for shutter clicks, mirror clicks, shutter button pushes, or images recorded to disc. The Canon software reads all of those separately but with a third-party read you don't know which number you're getting. They can be very, very different in these days of video, live view, and automated time-lapse photography (if I understand correctly, shots taken with a remote or cable release don't show on the shutter-button count).
My favorite camera story this way is a 5DIII we had serviced at Canon because after a month long rental it came back with dozens of hot and dead pixels. The shutter count was under 5,000 but it had hundreds of video hours on it. I had another that depending on what number you read had counts ranging from 20,000 to 70,000.