The 6D is JUST hitting the streets, in limited numbers...Ken Rockwell is already gushing about his new 6D...he loves the ergonomics of it. He's already calling it the "world's best d-slr". Seriously. He has become a real hardcore equipment junkie the last few years, having bought himself basically almost every high-end camera that his the market...Leica, Nikon,Canon. There really are NOT many 'regular user reports' on the 6D available just yet--that will take at least another month, to three months. I watched the Digital Rev (a TPF sponsoring vendor, BTW) Nikon D600 vs Canon 6D side-by-sdie comparison video, roughly 13 minutes of my life I will never get back...the 6D seemed like it was a decent performer...as long as Canon is extorting $3,500 for the 5D-III, the 6D ought to be their #1 FF seller,with a bullet.
FF and FX sales are around 5% of d-slr sales for Canon and Nikon, most experts believe.