That was with "Uni-Filters, not K&N's. I have survived many backfires, torrential rain with my triple K&N's. For additional peace of mind, K&N rain condoms are avaialable, and adjusting the bearclaw helps cover them.
After the rains, the oil may become depleted and require another cleaning.
Change your oil/filter every 5-6K (which is generally held around here regardless of K&N use).
The difference in going from a stock intake arrangement to a triple K&N has been dyno proven 10 RWHP SAE on a prieviously dyno tuned bike with Jardines. Pull the secondary plates and you will see a bigger advantage.
All of this info is available in our tech/how to section.