But given what it is that the vented loop on your heads is venting, it's probably a really good idea. On Eolian, the original vented loop fittings were cast bronze, and were fitted with a tiny version of the joker valve on the vent fitting. That is, the flaps of the duck bill would allow air to enter the top of the vented loop, but would prevent contents (or content vapors) from exiting.
But here in the real world, the occasional puff, or drop would escape. And you know, it doesn't take much.
So, I installed the smallest size thru hulls I could find at Doc Freeman's (a famous rabbit warren of a chandler here in Seattle, sadly now gone) into the insides of the bulwarks, and hooked up the vents to them with clear plastic tubing.
This truly is one of those very small projects that makes a big difference in the livability of your boat - especially if the head is near your berth.