Cold Air Intake - Mileage & Weather

I recently bought a 2001 Blazer LT and added a hi-flow Dynomax Cat-Back exhaust.

I have been considering a Fram Air Boost Intake kit (same as an AEM, as FRAM buys them from AEM).

A co-worker told me that he got good results on a Ford Explorer with an intake kit, however his winter fuel economy went down, as he stated the air was "too cold" in the winter.

1.  Can I expect any fuel economy improvements or drops with a Cold Air Intake?

2.  Are there any negative aspects when running a Cold Air Intake in sub-freezing temperatures?

Thanks!