I really need to see a comparison between 6P, Moto X Pure, and current 6. Those are the phones I need to decide between. Current 6 only b/c it should get cheap and the Snapdragon 820 comes out next year, but I'm not sure I can wait a year with my aging Moto X 2013.
I was looking at the same phones as you a few weeks ago, then the Nexus 6 price dropped to $350 on Amazon and I quickly jumped on it. Pretty solid phone for the price.
It'll have Marshmallow, so if it's cheap enough.. it's worth getting it and waiting for the 820 and hopefully new top of the line phones from Motorola and Google next year making use of them.