[incision]

>'I'm sure there are some exceptions among HN readers, but among the very few people in my circles on Android, all cite screen size as their main reason.'

I do some work with an org that offers a choice among iOS, Android, Windows Phone and Blackberry for thousands of company phones.

I find that 'normal' people are barely aware of any difference between iOS and Android. They care about screen size as you note and really practical things like battery life and reception. The only time OS becomes relevant is when someone wants to switch and worries about losing stuff in the transition.

Personally, what locks me into Android is the keyboard. Having used Swype for years now means that I can't even consider iOS until it has an equivalent.