Hey Anthony,
So, just to make sure there is no confusion, is it standalone as it gw+mgmt as one appliance or there is separate mgmt? If its distributed (separate mgmt), then you can absolutely do migrate_server export, then import into new server with desired version.
Its all documented below:
https://support.checkpoint.com/results/sk/sk135172
Now, when it comes to firewalls, backup will never work on a different hardware, as interfaces would never match, plus, Im sure version would not be the same. What I always do is this. Generate clish config, say from expert mode -> clish -c "show configuration" > /vaqr/log/hostname_config_date.txt, (just change the name) and would generate txt file with the clish config in /var/log
Then, you can use that file to copy bits and pieces to new fws, as long as interface name matches correctly.
After all that id done and verified, I always use below process, never had the issue.
Solved: Replace/Upgrade Cluster - Check Point CheckMates
Hope that helps!
Best,
Andy