If you look to the success stories they operate one type. Ryanair, Germanwings, Vueling, Wizzair and easyJet. Monarch are switching to a single type. Whilst I appreciate variants of one type may be a good thing when you have variants of two types, plus the a330 and the Dash8 thrown it, it is not going to be as efficient, not by a long shot. I wouldn't be surprised if the Boeings go, the a330 leaves the fleet and they become an all a32X operator.