We run a COP of about 3 atm (heavy users of hot water), but with off peak leccy at 7.5p being 90% of our ASHP energy usage, we're making significant savings vs gas. We also then run the dish washer etc during that off peak rate.
Then we don't pay a gas standing charge which is the icing on the cake.
With this setup, even a COP of 2, we would work out cheaper then gas I recon.