I don't think anyone mentioned that you can purchase the float valve with a soft viton seat. I used to sell valves when I was working and soft seated valves are more capable in achieving a tighter shutoff. Also note that to get tighter shutoff, more force is needed on the needle valve on the seat. This force can only come from a higher gas level. What this means is that initially you may set the gas level at 5/8 in. but over time any slight leakage across the seat will increase the seating force and the valve will then shutoff tight. Like Rex Reheis has suggested, there is an advantage to setting the level at say 11/16 in. to get the tight shutoff required. Note also that Rex stated that the gas level in the bowl is only needed to cover the compensator jet at all times, even during a hard stop. Sorry to get so technical, Ed