Dear all of you:
Recent Canon updates made me think about the quality vs. speed vs. weight issue. I´ve got to tell all of you that I´ve got no experience so far with last-gen digital backs. But still, I think it is worth to comment the possible war that can be stablished in the high resolution area.
On one hand, we do have the professional grade dSLR series which offer staggering shooting speeds with good quality. However, to be honest, most of the people I know and own those "über"SLR do not use this speed rate for shooting. I do not deny that there are people who actually need this speed. The only thing I would like to note is that this feature is not used as often as it should to make a profit out of it.
On the other, digital backs should be now cheap enough as second hand choice to be able to compete with full frame dSLR. And having weighed the Canikon samples, they are not as heavy as equivalent choices.
However, there is a third way [or better, there is supposed to be a third way soon enought], which is called the low budget medium format, namely, the 645Nd of Pentax. Were we taking for granted that it should appear sometime soon, it would be placed too close to the high end dSLR, and way lower than the Hasselblad, Sinar, PhaseOne and other combo or unibody stuff.
So, your choice would be
-High end dSLR
-Low end Digital Medium format
-Second hand Digital Back
Cheers