If it is a new trailer you might want to check whether it will affect warranty or not. Lots of discussions about this in the past.
But lots of people do use them apparently with no problems. I would guess something like 10-15% of 5ers I see have gooseneck adapters.
5th wheel hitch is easier to hook up. Just get within an inch and half or so and back into it and it will self align and latch. Most have front to back and side to side tilt. And there are a number of 5th wheel hitches available with no bed rails and that can be lifted out leaving the bed flat.