I echo the Mamiya love flowing on this thread. It would be the one, if I could only own one. I have the 50-80-150 and they are all superb. I'm sure the 65 is also; I've even thought about buying it, since the 50 feels a bit too wide much of the time.
I guess it comes down to your desires, and the financial aspects of the deal. I think a Mamiya 7 plus the 65 in pristine shape might set you back at least $1500-1800 (blind ballpark guess) to purchase, so it has that much value. You'd know whether---value to value---that matches the work you're doing for her. The camera, however, is not very liquid; there are a lot of Mamiya 7's available both new and used, and you can't count on being able to easily convert that full value to cash as an individual seller. Take that into account in your decision. A trade for a Hassy might be more feasible, and return more value, than a subsequent cash sale. (As I'm discovering with my RZ67 system, love it though I do.)
I think Sandy said it well--great lenses, fair body. Some have knocked its "plasticky" feel, but it's solidly built withal. Ditto the metering: I find that the hardest part is learning to trust the meter rather than constantly second-guessing it. For me it's been rock solid and quite accurate, even with the wide-angle lenses where its small sensing "field" said to act as a "spot" meter compared to the area of the scene being photographed. I haven't found that to be the case.
Hope this helps.