I don't know about the size and weight issue... though I haven't actually measured/weighed it out myself yet.
I calculated it just for kicks:
Hasselblad 903 SWC + 3 A12 backs: 2225 gm + lightmeter.
Mamiya 7II + 43mm lens and viewfinder, 65mm lens, 150mm lens: 2284 gm.
This Mamiya kit will fit nicely into 3/4 of the main compartment of my Billingham 445, with two lenses going into the two-segment divider.
Either system would be excellent, and I can definitely see the benefit of having multiple films ready to be used. However, the Mamiya was just dead easy to use. I guess I could've used an SWC in the same way -- meter and zone focus. But I wouldn't have been able to get a meter reading as quickly and the focus confirmation for closer subjects/wider apertures is easier with a RF.
I'm still going to sell the M7 kit, includes all three lenses.