I know what you mean, but a bigger keyboard is one of the reasons I want a bigger screen. I make a lot of mistakes typing (and especially trying to aim that cursor to correct them).There's no law that says Apple can't keep the digital keyboard the same legnth as the 4S and just have extra space to the left of it (or to the right, for a left-handed person).
I actually hold the bottom of the phone with my pinky also for no conscious reason other than comfort. But Im curious how it will be with a longer phone where you probably will have to grip a bit higher.If I hold my phone like that, I can't reach the bottom inch or so of the screen.
I "cradle" the bottom with my pinky and the phone just rests on my other fingers and then I can use my thumb. I guess if someone walked into me my phone would go flying into my face.
I have small girl hands and big girl nails though...