Rather than getting the Yamaha, I recommend the Denon 4311(or 12)
About the same caliber of receiver for about the same cost, but I think Audyssey XT32 is a deciding factor.
The Denon may have a bit less current reserves, but a quality separates amp like an Emotiva XPA-3 will wipe the floor with what ANY receiver can do.
Re: 70w into 7 channels.
I can think of exactly one scenario where this might matter, and that's a video game called Folklore, specifically the underwater level where all four surrounds are firing as are the mains.
beyond that, movies and music use surround speakers so sparingly, they may not even be getting TEN watts!! 70w is a lot for surrounds, especially side surrounds which are so close to you.