Mamiya primes are 35, 45, 55, 80, 120, 150, 210, 300mm. There are also zooms for 55-110, 105-210. I've seen a review of the 35/55-110/105-210 and 120 macro but nothing much about the others.
I tend to use 35, 55, 55-110, 105-210, 120 macro and 300mm, with a minimal kit of the 35, 55-110, 105-210 for travel.
I consider the zooms to be excellent. 35mm is very sharp and nicely built. 45, 55, 80 do not have the build quality and feel of the previous generation manual focus lenses but are sharp. The 120 macro is extremely sharp and akin to the Mamiya 7 lenses (43/80/150) plus it is a manual focus macro that is just superb (if I do say so myself!). 300mm is nasty in manual focus mode as it lacks feel and in general the MF AF sucks anyway. The 300 redeems itself by being very sharp with excellent resolving ability. Unfortunately I don't have Didger's expected tech specs to back it up - just my personal experience.
I'm surprised that people feel that the Mamiya will be similar in weight to the 1DsII outfit. In my experience, compared to my Nikon D1x outfit, the benefits and convenience of the Mamiya AFD/Kodak and lenses was better than the Nikon DSLR. It actually feels lighter although the Nikon was more 'robust' in construction. Ditto Canon I guess.
Your mileage may vary ....