Again, these are my opinions and others may disagree.
The gooseneck is not more solid; the fifth wheel hitch "captures" the pin more securely and allows significant articulation both side to side and front to back. Fifth wheel trailers are designed to carry the hitch load through a pin box. The gooseneck adapter changes the geometry of how the load is distributed quite dramatically. If you look at a gooseneck horse trailer there is considerable "webbing" along the hitch to distribute the load. The gooseneck adapter changes that to a point load. The offset you have creates a lever where the pin weight is behind the ball. My estimate is that situation puts an upward strain on the ball any time the front of the trailer goes down. I won't say that is unsafe, but would say "suboptimal".
My truck has the factory gooseneck/fifth wheel package which allowed for a drop in B&W hitch using cam locks. Very secure and not a permanent mounting. In fact, because the hitch breaks down in two pieces, I can take the whole thing in/out by myself. I'm sure there are fifth wheel hitches that suffer from "chucking" and noise. The B&W Companion is very quiet and there is absolutely no chucking. This hitch is great for off camber hitching. I have it set at the upper position and the clearance to the box is more than 6 inches and the trailer sits level. My truck is 4WD. See the attached picture that's my "avatar". I don't know if the same will be true for the gooseneck. BTW, chucking was always a problem with my gooseneck horse trailers. Another part of that solution is the Curt Roto-Flex pin box which also absorbs a lot of the motion.
You are correct that changing over will be expensive. Roto Flex will set you back around $700 and the B&W hitch another $1200. Ouch.
If you stay with the gooseneck, I will offer the thought that perhaps you should change the bottom part of the gooseneck adapter to the straight version which is compatible with your long bed and would eliminate the weight being behind the ball.
Best wishes and hope this helps.