We have had a hummingbird feeder for years. Have to refill it about once a week. Every one says you have to warm the water sugar mix for it to dissolve. I have found I just stir it a few times and leave it overnight to dissolve at room temperature.
I have switched to morena sugar for two reasons. Slightly cheaper and I can see the level from across the yard since it is not water clear. I think brown sugar would cost more and not sure if they would like the taste or not. You are not supposed to add food color so it is hard to judge the level from a distance..
Bill D