Thanks everyone for your inputs so far!

one quick note about the 645 referance. I have a Bronica ETRSI as well for the 634 side, in fact I have just about every format..minus 35mm. Just nothing really portable, and I cant afford a Mamiya 6/7 or anything like that.. so I was looking for something that would be great quality, and allow me fore than 12-15 frames.... and F1.2/ F 1.4 .. Now, if the quality is going to be just a huge let down compared to a 645... then I might need to rethink it...