I agree with you about boiling, I don't do it either. I do heat the water up a bit in the microwave first, just to make the sugar dissolve a bit quicker.
I think it might help make the sugar solution last maybe a day longer, but when it's 80°-95° degrees out there, even more when the sun hits it, it's not going to matter at all. You still need to change the solution every few days. Mold and fungus will form in that heat no matter how sterile your initial water was.
