Do you mean in terms of 'running' (fuel usage) costs, or are you taking into account the cost of buying an electric shower vs. buying a combi boiler?
If (as I suspect) you mean the former, what makes you think that?
Kind Regards, John
Because he is wrong. (If it was me he would say I was lying, but I am going to say he is mistaken as I'm not a bully).
Fact of the matter electricity costs 4 times as much as gas.