After many hours of flight in my aircraft using the GFC500, I report satisfactory performance. The unit does exactly what it is expected to do. Approaches are rock solid. Everyone, experienced pilots especially, are impressed.
Lateral fuel balance is key. In fact, a limitation. The manual says that there can be mo more than a 15 gallon fuel imbalance between wings.
My standard fuel load is full aux tanks, mains half full. I start my flights on the right main tank, level at cruise switch to aux. An hour into the flight I switch to the left aux (if a long flight), and fuel manage from there. Being as old as I am, I do not fly more than three hours due to bladder limits.
hope this helps.