I've never been to Sidmouth... too far. & far too dear... it seems to me that Southern folkies do Sidmouth & Northern folkies do Whitby ... Beardy is there, but he is a southerner... I don't think he's too bothered about Whitby but we will both be there... for the first part of the week at least.
At whitby I don't need a ticket, I spend the whole week with friends, I'm not sure I would have the same experience at Sidmouth, anyway because of work committments it has to be one or the other so the hour and a bit journey wins over the several hours one...