I am the fortunate owner of both of these wide angle options from Hasselblad. I bought the 40mm CT* lens first a few years ago as a cheaper alternative to the SWC camera with its 38mm Biogon lens. Recently I was able to acquire an SWC through a trade.
Pros of the 40 (on my 500cm) are slightly wider aperture and precise framing. Cons are it's size and weight. (I understand that the newer versions of this lens are smaller and lighter.)
Pros of the SWC are its slightly wider lens and technical lens quality, and it is a smaller and lighter package. Cons of the SWC are its imprecise framing through an external viewfinder.
If I had to keep just one, it would be the SWC because it is most suited to the type of photography that I do most often. Having the luxury of owning both means that the SWC is my portable walking around outside camera. The 40 is used mainly indoors, very close to my house, or very close to my car due to its size and weight. (My hat is off to anyone my age hiking with the older 40mm lens.)
Hope this summary of my experience is helpful to anyone contemplating going wide with Hasselblad.