Same here DuBro fuelers and have them in every glow plane i have. It is a hassle to use a fuel dot or my neighbor who is using his first thinks so anyway. Every guy at our flying field uses the DuBro system. Not one uses a fuel dot. I have seen 1 plunger stick though. But it was unstuck very easily. And if it sticks it is not going to suddenly stick in the air or anything of that sort. It will stick when you remove your fuel tube. Then just unstick it if it does very simple to do. Directions should be with the fueler. Make sure that if you mount it to the cowl you try to use something to stiffen the cowl a little though. Or your cowl could crack around it, from pushing the fule tube into it. a small piece of plastic works well just cut it about a 3/4" around and epoxy it to your cowl where your going to mount the fueler. Putting it onto a wooden suface works well if you can do that. And yes you can defuel with them just turn handle on hand pump backwards or put elec pump in reverse. Good luck however you go. Making a third hole in the fuel tank stopper for me is not what I want to do. Like you they are difficult enough just as is lol.