With a mostly exposed either upright or side mounted engine refueler valves are nothing but a pain, in fact when access is easy do not even use a third fuel dot line, stay with a two line system.

Only with an inverted or fully cowled engine would I ever even consider one. Come to think of it with a full cowled inverted engine I just run a simple loop of both the feed and muffler line out and right back into the cowl and short piece of tube inserted in a break in both lines to fuel.

Did I mention refuelers are trouble and a pain!

John