If you're worried about it changing the bank LSB, the quick installer only adds *new* LSB assignments (unless you modified LSB's intentionally on a non-Yamaha pack,or deleted a non Yamaha pack from your YEM and then loaded a new non-Yamaha pack in its place)
For Yamaha's own packs, that doesn't change bank LSB/MSB at all; so no worried. For non-Yamaha packs, the only way it could mess anything up is if you duplicated a bank LSB on top of one you already had previously installed on your keyboard (with a different pack), which quick installer won't allow anyway.
If you look at YEM, any new pack you install is assigned to a new LSB, and that doesn't even matter for Yamaha packs (only matters for 3rd party).
So, no, it won't mess up your registrations.
What *will* mess up your registrations is installing, creating registrations (using 3rd party packs) and then re-installing those 3rd party packs to a *different* bank LSB in YEM and then re-installing to your kb again.
So take note of which 3rd party sounds & styles you use (if any) and make sure you make a note of where they are in case you ever delete and reinstall the same pack; it needs to go back into the same LSB in order to leave registrations unaffected. If you use only Yamaha packs, then you don't even need to worry about this.
Mark