Solidsteel 5.5 rack: To fill, or not to fill?

I have read some conflicting comments regarding the filling of audio racks to dampen vibration, and now I'm a bit confused (believe me, it doesn't take much).

Opinions, recommendations?

FYI: The rack sits on a parquet wood floor which covers cement. All of my components sit on Vibra-pods, but amp is on Starsound Audiopoints.