I have an Aptus 22, on a Mamiya 645AFD (first iteration) and I also have a manual 35/3.5N—I bought it cheap ($100US!) on eBay in part because of fungus on the front element; it flares in contrasty lighting, so I am thinking of having it cleaned. It, like
all examples, is an old design and has severe moustache distortion, and quite a lot of sharpness falloff (which I can somewhat correct in Capture One). Anecdotally, there is a lot of sample variation. Long discussion about this lens
here. And
here is a post about getting distortion fixed on a non-EXIF lens.
For a cheaper alternative to a Hasselblad 40mm, I suggest looking at a
Bronica PS 40mm f4 in the SQ mount; this is reputed to be quite a good lens, and adapters for Mamiya 645 are available online.
One of these and a 24mm fisheye would keep me going!