Brian:

If you don't use flash, then the leaf shutters won't matter to you.

My preference for the Mamiya system is influenced by cost, but there are other factors as well.

Most importantly, the ergonomics of the Mamiya 645 cameras (and lenses) work better for me. I am very left handed, and with the left hand grip and focus assist lever, the Mamiya cameras work well for me. The Hasselblads don't work as well - for me.

A couple of other things that matter are:

1) The 55mm f/2.8, 80mm f/2.8, 110mm f/2.8, 150mm f/3.5 and 210mm f/4.0 lens all share the same 52mm filter size and all can be used with the same focus assist lever. I've settled on a favourite kit of 55mm, 110mm and 210mm lenses (plus a nice 45mm f/2.8) and they all are reasonably small and reasonably light and they work together really well.
2) I like the fact that with the left hand grip and terminal adapter, I have a shutter release that is off camera, and easy to release at very show shutter speeds. I also like the hot shoe.
3) I like the relative availability and relative low cost of standard accessories like filters and extension tubes.
4) I like the film insert system that Mamiya uses - all manual focus bodies and backs use the same inserts, and you can switch between 120 and 220 by just switching the inserts - which are quite inexpensive. The changeable backs (for the Super and Pro/ProTl) models are very reasonable as well.
5) I like the fact that with an electronically controlled focal plane shutter, I get consistent shutter speeds with all lenses. Unless you get a focal plane shutter Hasselblad, you will have to make sure that the shutters in all the lenses are kept calibrated in order to get the same result from them.
6) I particularly like the fact that the more esoteric lenses (even the slightly more esoteric ones, like my very nice 45mm f/2.8 N lens) are much more reasonable in cost than their Hasselblad counterparts.

I notice that your list of lenses doesn't include a wide angle. You should probably try the 55mm f/2.8 lens on the Mamiya before you discount that possibility.

Hope this helps.