I overlooked your request as needing information on the manual focus 55 and 45, sorry, all in info is about the AF versions, Mamiya. They are as cheap as the manual focus versions now or cheaper.
I can't speak to the Schneiders, but the 55mm AF Mamiya is a great lens, and often under-rated. No, it won't have the contrast that the newer Schneiders have but it's also a much older design. The 55mm at F11 is very sharp and would more than likely give the Schneider 55mm a run for it's money in sharpness. (I know others will disagree, and that's fair). The 55mm Mamiya will hold edge to edge on either the 180 or 160 as long as you are at F8 to F11. DOF is limited however and that one facet drove me crazy with the 55mm. With a DF body it's a great combination.
I never had a good copy of the 45mm AF and briefly owned the Phase One 45mm D lens and it was a good lens, but I still used the 55mm more. The 45mm Mamiya was a disappointment for me, never could get a good copy that held to the corners, however others have gotten them.
If the 55mm Schneider produces images like the Schneider Digitars (35mm or 60mm), then it's a touch call. I am still amazed daily at just how good these two lenses are, in both contrast, color and overall clarity.
Paul