I still say that adding sugar to the secondary is completely unnecessary. The alcohol content of your beer, combined with proper sanitizing practices are plenty to ward off any contamination at that point.
Adding sugar will only increase your alcohol content, without adding any flavor. It might make your beer finish out a little dryer, and could give it a wine/cider like flavor if you use too much. If that's what you're after, then go for it! Otherwise, I don't think it's necessary.