One of the Murphy's Law corollaries is "everything is harder than it looks". And he doesn't even know if at the end of the day having a COP of 1.20 means that it works or not.
If you found 1.2, it means it did not work according to the agreement: 4 or 6 was the threshold.
if your error bars are 20% you would only be at 1 sigma. (68% chance of it being a real effect")
You would prefer to do something that showed 5 sigma confidence.