After I was also shocked by Canon's pricing policy in terms of accessories / battery, I now also have ordered this battery for my G1X II. Usually enough for me a battery but as a vacation trip is pending, I wanted to be on the safe side, and continue to photograph while the original battery is charging.
So far I have the Patona battery charged and used repeatedly, but no difference for Canon battery has been able to determine. Should even a significant drop in performance be noted, I'll write that at this point. Until then, 5 Stars - TOP!