Unless you are dealing with some strange issue with a rebanded Motorola system that is not already in the RRDB, I wouldn't bother with making changes. You can basically only mess yourself up.
P25 systems don't use bandplans, and selecting one might mess things up.
I believe any Motorola systems requiring a band plan are already programmed in the database if you built your favorites list from there.
The main use of band plans are to resolve 800mz Motorola rebanding issues related to FCC spectrum changes.
Mark
536/436/WS1095/HP1/HP2/996T/996XT/996P2/396XT/325P2/PSR800/15X/others