J Shapes do one piece carbon foil and fuselage. It is very easy and quick to change over. Two screws and job done.
The foils are incredibly light and robust. The 120cm board, foil and 95cm mast weigh less than 6kg. I have 300 hours on the Freeride foil (high aspect) and about 100 hours on the Cruzer foil (low aspect surf). The small extra cost of having two fuselages is more than offset by the strength and ease of use.
I don't really get the separate wings and shims thing. It may be necessary for foil surfing. I don't have enough surf foiling experience to comment. It's certainly not necessary for kite foiling. The most I ever have to do is move my back foot a little. I do that all the time anyway.
I use the Cruzer a lot kite foiling in the waves and have experimented paddling into waves with it. I am having a box installed in my SUP to continue with the learning process. If that all goes well I will buy the larger C Wave foil and look into getting a dedicated foiling SUP or prone board.