Try living in Houston!
The mpg difference on my FX between summer - 17.9 mpg and winter 18.4 mpg has more to do with ambient temperature rather than engine heat soak.
I have used the OEM intake for three years, the Stillen Z tube and CAI for two years and the Spectre chrome tube with Stillen CAI for a little over a year now. There has been very little difference in miles per gallon between any of them. Heat soak really doesn't play into performance very much on a naturally aspirated FX. Once you are talking about living in extreme climates or elevations it might play into it a bit more, but in no significant way.
As long as you are not causing restrictions in airflow, any 3" intake that fits will work fine, so pick something you really like. Or love. Do up that Weapon R if you like it. It's called style because it's yours and nobody else's. This Chrome tube in this photo is not application specific. I found it, added two silicone hump couplers from siliconeintakes.com and it performs and sounds just as good as the Stillen Z-tube did. If you like the style and the price - it will be something you are proud to have.