What a conversation, guys...
I wonder if the OP is still around.
It's obvious that a Hasselblad 500C is a lighter camera, and if lightness and nimbleness is the most important factor, it's the best option. (Cue
@Sirius Glass singing "Amen!" in four different font sizes)
If you are going to shoot square (1:1) pictures and you don't feel the need to use a prism, then it's a no-brainer, a Hasseblad or any other 6x6 SLR/TLR.
However, if you're going to shoot rectangular pictures then the 6x7 advantage is realized over 6x6. And the Pentax lenses are magical, like the 90/2.8, 105/2.4 or 150/2.8. They're also very fast (compare 150/2.8 or 165/2.8 Pentax vs 150/4 Sonnar, for example) and have very narrow DOF. The P6x7 lenses, in my view, are what make the Pentax system great: Contrast, absolutely smooth bokeh, flare resistance, mechanical construction, ease of operation. Nothing beats a great piece of glass!
Note, also, that a Pentax 6x7 camera, fitted with the relatively-diminutive 90/2.8 and a waist-level-finder (or chimney finder) becomes a rather light, nimble machine. But you're stuck in the horizontal (landscape) format.
The most important thing, camera choice nonwithstanding, is to never use Pro 400H. Let it die forever.