The vast majority of times you will make a 1 hour connection at JFK. That's why they sell it as a legal connection. It just comes down to risk tolerance and the consequences of missing the flight. I'd probably risk it myself unless I absolutely had to arrive on the scheduled arrival day. But since you want to have a longer connection, why not rebook to the earliest RDU-JFK flight of the day and then spend the day in NYC? You could have a nice lunch, do some sightseeing and then head back out to JFK by taxi or train. It's Christmas day but I'm sure some things will be open.