This all assumes that the sugars are 100-percent fermented, which is a pretty good assumption, but you can see that when you move to other priming agents (DME, LME, brown sugar, molasses, etc.) you start to get more hand-wavy because now each of your grams of priming agent has more and more unknown unfermentables in them (water content, probably the biggest).
For using liquids to prime (I've used apple juice concentrate and maple syrup) I've had luck using the nutrition chart to get grams of sugar / serving and multiplying to get the amount needed for priming (eg. if 1tbsp has 20 grams sugar and I want 5oz of priming sugar (140 grams) then I use 7 tablespoons to prime)
Interesting about the different CO2 volumes from different sugars. I had no idea. I'd agree the 10% might not be noticed, especially if you don't have tight control over the amount of CO2 already dissolved in the beer.