I, and many others have a CAI, and in my experience the MPG increased.
There should be no issues with reliability, the old engine cover filtration is much more prone to any unfiltered air leaks than the CAI.
The mechanic at my local dealer ( where I only took it for a dynamic tire balancing ) said it was an improvement in his opinion.

In regards to you other post, a CAI will effect the cosmetic appearance of your engine bay.