I know i'm late to the party, but just for posterity's sake if we ever revisit this:
It would be an optional field, and like OP stated, it would help with gender pronouns. If you don't want to specify, you don't have to, and it's not required, but you also shouldn't get your panties (or boxers) in a bunch should someone mis-pronoun you. IDK why, but a few people have gone off about being referred to as the wrong gender. If it is that important to someone, they can fill out the box. No verification needed, b/c it's not used for anything anyways. If you are a female and want to be referred to as a he, it does not detract from the forum. ditto for vice versa