I personally have not done the gsx swap. Simply because i mainly wanted to stick to original bmw parts.
When it comes to handling the lowering was for riding posture which in turn helps with handling. My personal preference for handling might not be te same as yours.
But throwing the bike around in corners itself and being able to have a beautiful lean angle changed/improved for me with the wider wheel and rounder tyre.
Eventho i build the bike to my liking it was still ment for riding and across countries.
