There are so many rumors out there, it is hard to know what is truth and what is not. A couple of thoughts:
All three bands being supported, I would have to say yes. Apple would shoot themselves in the foot if the iPhone 6 did not support all three. There are so many people awaiting the release. Samsung's sales are poor right now for the S5 due to people waiting for the release of the next iPhone. If the i6 is a home run, Samsung will lose a fair amount of market share.
I will say that I am going to purchase the 5.5" 6 due to the amount of documents I have to read through for work. I also hope that if the rumor of the larger i6 having128GB of memory is true also.