I did alot of reading on both forums before cutting up my airbox. I get alot of comments that alot of people have no problems riding in the rain, even with the filter exposed.
Nevertheless, I installed Outerwears as a precaution.
On my recent trip to Thailand, I was caught in heavy rain on my return trip. Just about 40km in the rain, my bike started stalling every km or so, and it had to do this at a road where there was no shoulder to stop at with large container trucks whizzing by in the rain.
I will be looking out for a new airbox and putting it back on.