I am planning a trip for next May, arriving about the middle of the month. Of course I have read about "unreliable" ferries but do not want to be overly concerned. We plan to ferry between Santorini and Naxos and then from Naxos to Athens. I know these are main, daily routes and I am thinking May is not an "active" weather month. Can I be reasonably certain of making plans for specific days for booking hotels and then the flight home? Thanks!