When I had my O2 Sim in my iPhone 5, I had the option to select 2,3 or 4G. I know the 4G wasn't relevant to the 5, but if I know I was going to an area with limited coverage I would select 2G to conserve battery etc.
On the iPhone 6, there is only the option to Enable 4G? Which I leave it disabled unless I know I'm going somewhere that has it.
Would this use more battery as the phone would be constantly searching between E and 3G?
When I make the 5 a 4G handset, e.g inserting a 3 Sim I get the same option to only Enable 4G.