Because the decoding of DVD-Audio and SACD happens externally to the pre/pro and because that decoding is purely 5.1, the back channels will remain unused. The only way to change this would be to add a layer of signal processing to the 5.1 analog signal path, something that has generally been avoided (which is coincidently why there's typically no bass management on 5.1 analog inputs). The 5.1 and 7.1 surround modes (like DPL II, Cirrus Extra, and the 5.1 and 7.1 stereo music modes) should only be available for digital inputs and in some cases analog stereo (which undergoes an A-D conversion first).

The "back" inputs appear to have been replaced by a switch to enable/disable the 80Hz crossover, by the way.

I could be wrong (happened before!), but I'm pretty sure about this one. They could theoretically send the same signal to surrounds and center surrounds (left surr. and left back, and right surr. and right back), but I doubt that they would.

If they'd kept all 8 inputs, you could have used two Y cables to connect your 5.1 external device (DVD/A or whatever) and had the surround signal sent to all four of your rears, if you preferred. Or not.

I think it would have been nice if they'd left all 8 and put the crossover switch somewhere else, if nothing else than just for the futureproofing mentioned earlier in this thread. DVD/A & SACD are both 6 channel discrete formats, true, but who knows if/when either of them or their successors will be extended to add two more discrete channels.

Stereo LFE outs a la the ICBM would have been nice, too. :-)

Just my two cents. Of course I'm under no delusions that any of this is changing before the 950 ships.

I agree with you that we shouldn't expect any of the items you mentioned to materialize on the 950's feature list at this point. Some of those are things that may appear in the "high-end" pre/pro and may have fallen victim to budget on the 950, though.

Or not...