A lot of David Line's recipes called for demerara sugar, and also soft dark brown sugar. They do leave some residual flavour (which is not unpleasant as I recall), but should be fine for priming, if that's what you have lying around.
i use 2 1/2 OZ for 40 pints in a corny , not sure if youre using bottles but I woud have thought a teaspoon in each would be okay but better confirm with someone who knows for sure.