You can only blame Apple for doing this. They should have had demo units right after the announcement. People would have had 2 full days before pre-orders went live and another 7 days before going into the store to make a logical decision. The returns and exchanges are going to be massive just because of size. And people that really wanted the iPhone 6 plus will be screwed because people are returning them for the smaller units which apparently Apple made more of. But this will allow Apple to have huge sales and they now have plenty of refurbs for warranty swaps.
I was one of those people that wanted a 6 plus but after playing with both for an hour I went with a 6. Got tired of using huge phones so I'm going small on the go and using a tablet at home.
In all honesty Apple should have made one 4.7" model this month and then release the 6 plus in 6 months. This is one thing Samsung did correctly with the Galaxy and Note series. There was no arguments over which one to pick.