Just know, you won't get high off of the fan leaves. But, I believe they can offer nutritional effects if brewed correctly. I know the leaves have natural antioxidant effects. The darker leaves may have more of this due to what gives them that color. So, some benefits could be:
Anti-inflammatory
Non intoxicating (if that's what you want)
Nutrition (fiber, Iron, Magnesium, Omega acids, etc.)
I haven't tried brewing fan leaves into a tea yet, but I love using sugar leaves to make canna teas!