I prefer metal intakes. I've had 2 K&N's fail on me before I moved to a MacPerformance intake. Its a big chrome tube and has a LOT of airflow going thru it. My heads have been extrude hones and those K&N intakes didn't keep up with the Mac intake at all. One suffered from extreme cold and started to crack. I'm glad none of it went into my intake.
Using Digimoto, the temperatures read off the IAT sensor between a Metal tube and a Plastic one is Minimal ( less then 5 degrees ).