Disc vs deep section rear wheel for TT

[dome]

Is there a big advantage in having a disc rear wheel over say a Zipp 808 rear wheel in a TT?

[11ring]

Is there a big advantage in having a disc rear wheel over say a Zipp 808 rear wheel in a TT?
HED has drag data on it's wheels. It will give you some idea about the differences.

http://www.hedcycling.com/about/