Baking times are never accurate. There are so many variables. Your best bet is to put a timer on for 45 minutes, and then check on the loaves from there.
I can usually tell a baked good needs to be checked on from smell. Is the loaf a quick bread? Or yeast risen bread? If it's a quick bread you can confirm doneness by inserting a skewer in and it coming out clean, and also by touching the top of the loaf gently and having the bread spring back up.
Brown sugar is delicious in banana bread! It's sugar that just hasn't been refined as much to take out the molasses. If your bananas are very ripe I'd cut back on the amount of sugar to make it less sweet. But that's just me, personally. Brown sugar also has a bit more moisture content to it, so if the bananas are really soft you'll have very moist bread.