I always use the key, mainly because of my other bike, a Triumph Daytona.There’s a quirk with them where damage has been known to happen to the ECU because of using the kill switch. When using the key a relay is activated keeping power to the ECU allowing a shutdown sequence to occur. This doesn’t happen using the kill switch which cuts power immediately, and has been known to cause irretrievable corruption of the ECU.Not something you really want, and would prove pretty costly.