I would imagine stalling your car constantly, (due to stumbling from an incorrect air/fuel mixture), can't be good in the long run. If you absolutely have to have it open, do what 95Ride does, or just run it open all the time at your own risk. Some cars seem to fair better than others.

Personally, I would just say keep it closed. (This topic has been beaten to death numerous times). The performance gain (if any) is going to be minimal and won't be worth the hassle of f'ing up your idle and causing your car to possibly stall. I was like you all when I first got my car and my HKS arrived via UPS. Installed it and tested it recirculated, then was curious and ran it open around my neighborhood just once.....which ended up leading to my car stalling, fouling out a spark plug, and a dead cylinder. I learned real quick not to do that any more. So, pick your poison. I run mine closed.