Looks like your big concern is whether you’ll have hot water in the afternoon in which case you’re biased towards the E10 tariff. However, if you have a well-insulated water tank the water should still be hot in the afternoon from the previous night provided you’re not using all the hot water in the morning – only you know your daily habits. I don’t have a problem with keeping water hot, as I have a thermal store system where the overnight electricity is used to heat water in a highly insulated tank – this “store” of very hot water is not used directly but heats the water passing through a coil immersed in the store. My gut response to your dilemma is that you should stick with E10 as it provides enough hours overnight for your storage heaters and hot water heating in the afternoon. You don’t say what region you’re in so we can’t tell what hours you get the E10 tariff.
Have a look at the recent prices in your region under the “Prices” link at the top of the page.