Do you have an offer from Easyjet or are you just contemplating applying? The application process is a mess. If you actually had an offer, then you should consider yourself lucky.
My impression is that the rostering situation will improve with time given the threat of pilot exodus if it does not.
Part of your thinking should be based on your fleet type at Flybe. If you are on an expanding fleet like the Q400, then you might want to consider the benefits of staying. However, if you fly the 146 (with the potential for a reduction in 146 flying), then I would definitely consider leaving. Flying a new Airbus wouldn't be a bad deal...
I don't work for Easyjet, but I would also like to know how your base is determined (i.e., Stansted, Luton, Liverpool, etc.). That too could impact your decision if Easyjet wants to move you to a less desireable location and you have school kids, etc.
Good luck in your decision and keep us updated!