I wonder if you're just looking for a difference.
I don't have an iPhone 5 to compare and I did a comparison on my iPad 3rd Gen which is not the same thing, but there was no noticeable difference. And when I did use my friend's iPhone 5, the touch response wasn't so vastly different or superior for me to take any notice. In fact, if anything, I noticed the weather wouldn't launch from the Notification Center even after a few taps. I posted about this a while back. When asked, my friend said yeah, sometimes the device isn't responsive or the action doesn't happen on the first tap. Sometimes it requires more than one tap. I've noticed this oddity on my iPad 3 too. And they are taps that are registered (the icons gray out). The action just doesn't actually follow.
So, I don't know.
Check out Pocket Now's iPhone 5 vs Nexus 4 video. A few times, he does comparisons of what apps launch faster, which reorients text faster when browsing, etc., where you can see him touching both screens at roughly the same time (he'll do little countdowns). There is so little perceived difference, if any.
http://www.youtube.com/watch?feature=player_embedded&v=MIWYp6ZXe-s
And if there is in any difference for any side's favor, the difference seems extremely minuscule. I wouldn't worry about it too much.
PS. This video was made before the Chrome update that came out a couple of days ago.
EDIT: After watching the vid a second time, you can definitely see him missing keys a few times on the Nexus 4, which alludes to my point earlier about touch points being smaller. Not sure why that is...