sevo
Fokutorendaburando
Sometime in near term future some thoughts to ponder: if you continue with a Mamiya 645 system, the better lenses available are the 35mm N, 50mm Shift, 80mmF1.9, 110mmF2.8, 145mm SF, 150mmF2.8 N, and the 200mmF2.8.
All M645 Sekor 35mm versions have the same schematics - the only thing the N will give you there are better coatings (and in the final revision, doing away with the annoying silver trim on the focus ring). The 45mm is the one that was completely redesigned between C and N. The 80mm f/1.9 is the speed king in medium format, but if small DOF is not your primary concern, any of the other normals is just as good, each of them strongest in one discipline - the 80mm/2.8 N is the highest contrast, the 80mm Macro the highest resolution and the 70mm/2.8 is a true normal (i.e. with the focal length the same as the format diagonal).
The 145SF is nice and the bokeh king of them all, but with so much focus shift that it has (and needs) a extra (barrel push) stop-down mechanism for focusing. Personally I find it near impossible to use outside bright sunlight or studio light situations.