Rob & Chris,
     Chris, I concur with all you said on the subject, your posts are always read with interest.  I've done the same only the Carb Air Box is of aluminum (to minimise induction fires),  with a K&N Filter for all intake air (a la Mooney), and an Alternate Air spring loaded door beneath the "Box".  
     Had occason to need the manual control of the spring loaded door, when a RON with rain had the filter wet, on climb out the next AM got to the freezing level at 10 M ft. and things started to go quiet,, apparently the spring loaded door had frozen shut also. Manually held the door open with the Belsen cable til I could get a lower clearance..
     Don't have performance data, but got first place in the 235 Mod Class for 4 years at Redmond, and this Mod had to help..  Regards & Seasons Greetings !!  Don SKeele