I also would have bought the Marantz apart from the LPCM limitation, as 7.1 channels is a mandatory requirement for me.
Quite frankly, I find it unbelievable that Marantz can spec this product with HDMI 1.2a and then not have ensured that 7.1 LPCM inputs were enabled. And further adding fuel is that after many weeks of this concern being raised, Marantz still cannot comment why not. Whilst I appreciate that Marantz US is a sales / marketing arm, you would think 24 hours for emails back to the engineers in Japan would clear this up.
Like a number of these CE companies, they don't make any of the individual chipsets, such as the HDMI receiver chips. And it would appear in the case of Marantz, they don't know what is enabled or not in the chipsets they are using. Mind you, they aren't alone.
I'd get the Yamaha unless you are, and always will be, happy with 5.1 channels.
And there have been a number of reviews of both in Europe, particularly in Germany. Both rate well, but the V1700 is more consistently rated higher. It would seem there is little difference in audio between the V1700 and V2700, and the differences relate more to feature sets. But there appears to be a difference in audio quality between the S7001 and S8001. I haven't been able to compare these at a dealer. As others have mentioned, it would appear that the Marantz has a warmer, richer sound than the Yamaha. Which is right depends on how you feel your current speakers and room are working together.