If you are riding in rain a lot, and you have an airbox, use it. Once you jet the box properly, the difference in performance will not be so great. The character of the motor will change slightly, to a more torquey low-end rather than a high end zing, but that is usually better in traffic anyway.
I did not like the Uni pods I had. They dried and crumbled and little foam bits were geting sucked into the engine... and yes, I used the Uni brand cleaner and sticky oil as directed. Sunlight U-V and maybe some of the ethanol vapors took a toll on the foam. I also went through similar isssues with K&N, but not quite as bad. Now I use the disposable dry pods. They look much nicer, cost very little, and require no maintenance or messy/expensive chemicals.
I also have two other bikes with airboxes. They are the rain-day choice.