K&N do offer a set of RAIN covers for the 2780s.
imo - worth the effort - it will also need the heavy duty MUCK off the filters them selves.
Put them on and leave them there. Unless you plan monster mod's to the engine they wont affect airflow much.
I have had my R3 sat in pissy spring weather in the UK for days and ridden though massive "pan-Iberia" thunderstorms and no issues with water - I have an OZ-Claw over it.
Other things filled up with water but the filters stayed perfectly dry.