I agree that 5" is the sweet spot (for me). That said, not concerned about the 4.2 upgrade, or even 4.3 at this time. This device is just so darned buttery smooth and gorgeous that I simply don't care. I have a hard time not looking at it. ("A thing of beauty is a joy forever." - Keats)
I've got hands the size of meat platters so I like 'em big. But my GN2 stretches my hand to the limit (yes, for one-handed use - I could do it.) I'm afraid 5.8" or 5.9" will be too big even for me.