I bought my 645zi from a camera store in Japan. From here not there. It was listed as fine but came closer to nearly new, no marks, case, lens hood the works. My evaluation after shooting a couple rolls at home was during trip to Italy. I found I could get about 95% of the shots I wanted. I could have used a wider angle and a longer tele. The biggest problem was the closest distance I could get in. When you're used to getting right up close having to stay back a meter is a problem.
The zoom is great, the focus is spot on, it's a keeper. If I were to go the wide angle and long telefoto route I'd have to use multiple lenses. Traveling with my wife doesn't lend itself to a lot of lens swapping. Although she spends a lot more time composing her Nikon Digital camera and iphone! The field is closing up now. It's better than having someone waiting on me.
So yes I'd like a wide angle too as long as it's light and can go close in. There isn't anything wrong with my Mamiya 645. I'd have to carry extra lenses or my 105-210 ULD plus a wide angle like my 55mm or wider. I did on a Paris trip. The handle bracket works superbly. A light tripod works too but the rotation accessory is an added weight. I have one and rotating around the lens axis is great.
A Mamiya 711 with a wide and tele would be nice.