I have heard that there are people who have been an crewman in each service and I was hoping to tap into their experience and what made them make the move.
There are a considerable number of ex RN crewmen on the RAF Chinook fleet, the extension of service to age 55 was one of the more obvious reasons to transfer (but I think the RN is now offering extensions ). I'm unaware of any ex RAF crewmen that transferred to the Royal Navy, (but that doesn't mean there isn't).
Just contact the Squadrons and ask for a chat.