It can help illustrate the issue. Your brain is surprisingly good at adapting to lag that you only notice once its no longer there. And comparing to another iPhone would be interesting anyway.
On the topic of your brain adapting for lag and delays (which isn't necessarily the case here) if you ever watched a movie that the audio of someone talking seemed out of sync at the beginning of the movie but fixed by the end it more then likely wasn't fixed. It was your brain adjusting to what it feels should be happening vs what is actually happening. Boring but interesting.
Interesting. Well, I played with both for half an hour and both seemed fine, fast and cool. Enough for me, but hey, want slo mo - do slo mo.