I am sorry if I am misunderstanding this, I was told that the 30% maul damage did not work unless you were in surging charge and that the tooltip was wrong. This may well be an error on my part. Will run some tests.
The only thing you need to be in Surging Charge for is the Induction stacks for your shocks. 30% increase to Maul crit damage is the same no matter what Charge you use.