The Break/Mute function assigned to ASSIGN SW should NOT change if you change styles... only when you change UPGs (registrations).
There are a couple of workarounds... If you are creating ALL your own registrations, start from a blank template UPG with controller assignments set up and saved the way you like them, then you won't have to enter these things.
OR... you could get a copy of the Session Manager software at Roland-Arranger.com (it's fully functional, you only pay to get expanded batch processing, so you can try it before you buy it - and it's cheap, too!) and copy the controller destinations, split points, yada yada yada to as many registrations at the same time as you want. It is virtually indispensable for PC G70 owners.
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An arranger is just a tool. What matters is what you build with it..!