The move to v5 by itself wasn't too bad but at the same time I decided add some z-wave. Honestly, the z-wave stuff has been a PITA with some devices having various compatibility issues. Once I made sure I had sufficient coverage for z-wave plus repeaters I have not had issues with the Zooz motion detectors. I don't know yet if the z-wave issues I'm having are related to 5.x or the specific devices.
As for the upgrade to 5.x, the programing changes I made were related to motion detection and related how quickly the lights come on. This was mostly self inflected and a labor of love. In 4.x I had motion detectors directly linked to lights as you have and was using the adjust scene in programs to adjust on levels at various times of day. In 5.x, after I made the required changes to the adjust scene, I realized the ISY was trying to write to motion detectors every time the scene was adjusted. They are battery operated so the writes failed, but technically the on levels did change because the change is on the responder side. This issue probably existed in 4.x but I just didn't notice. So then I moved to controlling Lights On through programs and addressed the delayed on situation a little differently. I added sensors and programs to "pre-light". As an example if I come down the hallway leading to the kitchen, then the kitchen lights come on at 30%. If I don't actually go into the kitchen within a minute then turn the lights off.
I spent a whole bunch of time working out all the logic, motion sensor placement, etc but only because this is a hobby. There is probably a better way to do all this but I was in it for the fun.
If you don't have the need for any more complicated logic or not in it for hobby, then my recommendation would be to stay with what you have. If you love to tinker, then clear a weekend an dive into 5.x. Read through the documentation carefully, backup, export you programs, etc. I recommend taking screen shots showing with programs are enabled and disabled as you will need that info. Make sure you manually disable any previously disabled programs after the upgrade. Also recommend taking screen shots of any programs using Adjust Scene. Most my programs converted just fine other than those with Adjust Scene. Comments where automatically inserted into programs that had adjust scene and they were left unsaved after the migration. It wasn't too hard to figure out from the comments that were inserted how to recreate the adjust scene lines. I only had one z-wave device prior to migration so I just reset the z-wave dongle to factor default before the migration and started setting up z-wave from scratch after the migration.