You're right about IOS4/5, that was an oversight on my part. I guess I lumped them together because when I am battling the IOS4/5 incompatibilities, I am doing it in XCode. But you are absolutely right the two are separate.
I have used the Android emulator and done work on Android. It is quite fragmented as well. But I am working right next to another mobile developer for the last 2 months, he is on Android and I am on IOS and he hasn't felt as much pain with the emulator or supporting different Android versions. Then again, maybe he's just smarter than me.
Please upgrade to Xcode 4.3.2 - Apple released an update to fix the bugs 4.3 and 4.3.1 had. It is much more stable than before.
I have had some problems when the debugger was connecting to the Simulator, but most of the times it was because of other things which were installed in my system.
I know that Xcode4 used to be shitty and slow and used to crash. But Apple has come a long way from what they started.
Even though Xcode4 is a little painful to use on a small screen, still it is far better than Xcode 3.
Android, on the hand has different screen resolutions, different specifications and that alone is a pain. I have not even started with the OS fragmentation yet.
Many others have already answered the problems you were having with iOS4 and iOS5 backward compatibility. I think, you should spend a little more time with Xcode before making a judgement call.
Interestingly I have encountered ALL of the bugs from that article. However I don't mind Xcode that much, when I start to get frustrated with it I remember that It could be worse, it's not like Androids tools are much better, last time I used Android the emulator was unbearably slow.
I have used the Android emulator and done work on Android. It is quite fragmented as well. But I am working right next to another mobile developer for the last 2 months, he is on Android and I am on IOS and he hasn't felt as much pain with the emulator or supporting different Android versions. Then again, maybe he's just smarter than me.