Big Screen iPhone - Good For Apple's Margins?

OK so I'm just thinking off the top of my head here, and I'm sure there's probably some logic I'm missing...but wouldn't a big screen iPhone give Apple a chance to maximise their margins?

I.e. Create a big screen variant at minimal extra cost, but charge a fairly hefty premium for it over the standard model.

While for me personally it would take more Android-like features to get me to switch, I see people on the android army often say that they'd switch, but screen size is the big limiting factor now.

That's anecdotal I know, and is also focusing on a particular type of user that frequents sites like this, but then I look at the big uptake in certain markets of things like the Galaxy Note, which at least to some degree would seem to evidence a desire for bigger screens.

Of course Apple's own research knows the answer to this question far better than any of us do, but I just wondered what people thought. Specifically not whether you'd like a bigger iPhone, but whether they should make an additional one in a larger size.

The big downside would seem to be brand dilution, especially with the 5C coming. But as I said initially, it does seem like it could be an opportunity to increase their margin per handset and pull in a few more customers.