Having said that: Im not decided yet which it will be, 6 or 6 Plus. Thats why I ordered them both. One will go back. If I can/want to handle the dimensions of the giant then I will keep it not only because of the bigger screen for displaying content, the better cam and the better battery. Its the keyboard that will play an important role in my decision.
I'm guessing there will be a growing number of 6 PLUS phone returns once people get them and try to live with them.
I have a iPhone 5 and a Lumia 1520. I absolutely love the Lumia 1520, the screen is gorgeous and is overall a nicer device to use. BUT, there is nowhere for me to keep it day in and day out. It's too big for my pockets and I keep my iPhone 5 in a horizontal leather case on my belt for easy access. Because of this, I would have to make major compromises with the 6 PLUS. My iPhone 5 continues to be my main phone because of this. Hoping 4.7" isn't going to be a problem on my belt.
I think a decent percentage of people will find the 5.5" cumbersome and will return.