I went with 501c and I've considered RB/RZ.
Since I travel with my kit, the hassy made a lot more sense due to weight. With 80mm back it weights 1.4kg. Add 150mm lenses and also my 35mm kit + lots of film to last 2 weeks while overseas it starts to get pretty heavy.
Also it's very easy to hold it with my left hand and access all of the controls with my right hand.
I would say if you planning to take your gear out a lot, go with hassy due to weight.