I have both, and I gotta tell you, I hate to cut up a cowl to put in a fueler or a dot. Most of my recent planes have just been equipped with a third tank line, and I plug the line with a short copper wire plug.

The plug can have a loop, if I want to hang it inside the cowl. Mostly I cut the line to just clear the cowl, and leave it hang.

My problem with every one of my fuelers is the O-ring. One got sticky, but it's easy to pop into place. The O-rings are easy to replace, but difficult to find (don't buy Butyl, get Neoprene or Viton.)

My problem with dots is cutting into the cowl to mount them. I'd just rather let the line hang down.

To each his own.
Dave Olson