I believe their Peak Rate is 20p per KWH so pretty penal, they give you an extra hour Off Peak over Go at a very similar price but then claw it back the rest of the day. I think they're only offering this because they're losing Customers hand over fist to Octopus so for me sticking with Octopus is a Financial and Moral decision as without Octopus there's no way they would be doing this but everyone makes their own call on these things.
That's a good point to be fair, my current rate is 15.25 p kWh and Octopus is showing 16.01P, does it reduce once you get onto Go? It's chicken and egg isn't it signing up then waiting to get the smart meter!