Turbos will have less variance only because there are 9 players instead of 10. In SNGs, your variance will always be near the same, regardless of your ROI because it depends on your place percentages and 13%/13%/13%/61% yeilds a variance similar to the one that 10%/10%/10%/70% gives.
Somebody around here learn some math for christsakes.
The square root of the sigma-squared is your standard deviation. That's why your standard deviation only increases as the square root of the number of games you play, while your profit increases linearly (ideally).