I own three: A Radice Aerobilliard, a Bruce Weaver, and a Negoita conducta.
I will be honest - I have not noticed any real difference.
That said, this fellow did an experiment and did show some measurable difference in the temperature of the smoke, particularly with respect to the ungodly large (and hideous) second-chamber in the Anthony Harris pipe:
http://tobaccodays.com/articles/100-proven-reverse-calabash-pipes-provide-a-cooler-smoke/