I switch between regular 6th gen iPad and iPad Pro and I have to admit the screen refresh rate is the thing I do not notice at all. With the transition I notice far more the dip in performance (in terms of CPU and RAM) than anything else. Here are the things I notice:
1. Lack of laminated screen - it affects the pencil usage
2. Less RAM - a lot more tabs and apps reloads, some apps crashing (Books, Notability, issues with export videos from Keynote etc)
3. Chip difference - you can feel it both when it comes to performance/execution as well as GPU. For example you can use LumaFusion for video export, but the experience of scrubbing the timeline and seeing real time what is going on is not always the best.
4. Audio differences - two speakers vs four.
Overall I personally would not say that the screen refresh rate is something that is vital for me. Most probably it contributes to a nicer experience on the pro, but it is not the first thing I notice when I switch between the devices. So I personally would not put it higher on my list for features I need and am looking for.