Did a search and couldn't find anything. Does anyone know if there's been any aero wind tunnel testing on a Disc Wheel w/ Disc Brakes vs deep dish aero disc brake wheel?

Its common knowledge that there is an aero penalty for a cassette on a back wheel. But with a disc wheel w/ disc brakes, is this a double penalty seeing as the left side will also now have a protruding metal disc? Anyone have any numbers? Perhaps it's a minimal penalty? Or perhaps this is why many pro's are running deep back wheels vs. disc wheels with disc brakes?

I want to try and find out some aero-related information as a baseline before spending a tidy sum of money on a new TT disc bike and disc wheel set up. And I do love riding a disc...