I've got a utility trailer 1 7/8", boat 2" and my TT 2". I've been using my convert a ball for more than a few years, though not with the TT. I've got a 5 1/4" drop hitch for the smaller trailers and a flipped 2" hitch for the TT.
No problems with any of them over the years but I'd be a bit hesitant to use the 2 5/16" ball for any significant amount of towing. There is a bit of "slop" with each of the balls and I wouldn't want that when pulling something with the weight that a 2 5/16" ball is normally used for. Particularly something that requires a WDH.
Just my .03 cents. (normally .02 cents but my wife game me a raise in my allowance so I'm spreading the wealth!)
