[Damselfish]

Purge valves are one of those things that seem like a good idea at first but after awhile, maybe not so much. You may notice the vast majority of masks for sale are not purge masks and you won't see that many people using them.

Some people like them for various reasons, like they really prefer clearing that way instead of the usual way, and have no problem with them. Sometimes because they have facial hair and have trouble with leaking in any mask, and find this better. Or it was simply the mask that fit them bast.

More people seem not to like them. The valves can get in the way of pinching your nose if you clear that way, or they might rub your nose. They can fail or fall out though it really doesn't seem to happen too often. They can just get floating crud stuck in them and leak. Often masks with purge are a bit higher volume which is less desirable, the field of vision may not be as wide and it would be a bit more effort to clear the normal way.

I wouldn't usually suggest buying one, but if you've already got one and it fits well, I wouldn't worry about it too much unless it's bugging you for whatever reason. You can always keep it as a backup if you decide you want something else eventually.