If we assume there was a 50-50 split in sales, that implies 2 million 6+.
The problem there is it's not 50/50. It's more in the 3-6:1 ratio of iphone 6 to 6+. There are some data points in analyst notes that point that out. Some of that may be supply driven inherently, but the 6 will be much more popular. The vocal sliver of the internet here may seem dominated by the 6+ but it's not representative.