Final maximum print size might help you make a determination. The negative from the RB67 is big, but the camera and lenses are significantly heavier to carry than those from a 645 system. So, factor in how much hiking, if any, you will be doing.
Yes, the prices on the RB gear are ridiculously low now for such good quality. Another thing I like about the RB is that the images are very easy to focus using the waist level viewer, which is not always the case with some cameras.