Yes a manager confirmed Eco 7 will apply their usual tariff to E10 meters. Don’t be fobbed of by call centre staff, they might not understand what E10 is. I couldn’t get the one I first spoke to off the idea that E10 is always three rates. When I asked to speak to a manager all was sweetness and light.
I think Eco 7 are almost certainly the cheapest provider at the moment.