Using granulated sugar in chocolate leaves it gritty and unpalatable. However if you would like to use an alternative sugar such as maple, coconut or rapadura at home, consider turning it into a liquid sweetener by making the following sugar syrup recipe:
The longer you boil it the thicker the syrup will get when it cools.
A good consistency upon cooling is that similar to agave syrup.
This may take a bit of practice to get the right consistency however it does open up your options for sweeteners if you do.