Personally, I'd go with the Mamiya just for the simple fact that it has interchangeable backs, and hard to beat Mamiya optics. Cheap way to get into medium format, too.
Mine was also a little hard to focus until i pulled the top off and cleaned all the surfaces with a q-tip. Made all the haze disappear and also made the focus spot higher contrast.
I pulled it off and cleaned with qtip. The is one surface that looks cloudy but I didn't use any liquid in case it's one of the translucent mirrors. Do you know which ones are the translucent mirrors looking at it from the top viewing position?