Full uptime on gauss barrel is a DPS gain. People do have varying numbers with stance dancing, but there's so many variables with MCH DPS that you can get a variance of 10-30 dps on parsing unless the proc/crit rates are nearly identically to each other.

To me, trying to stance dance in and out of GB when you can otherwise fulltime it (given that the fight allows for it) is putting more burden on yourself for little to no gain.