Aaron,
I would check with HE, someone that carries GDFB maille, or anyone of our maille-makers here on the Archive. Lonewolf Chainmaille made my last one, but I have had a number of them over the years (if you can get rivetted or welded, that would be the ideal).
On horseback, it is impractical (okay, pretty damn impossible) to wear a cup as it impedes your ability to ride. Brayettes (a maille skirt) gives us decent protection and can be draped over the front of the saddle.
While direct "crotch shots" are very rare, many times when lances hit tip-to-tip (as in the case with Rod and I) the lance is directed away from where you are aiming. In the case with Rod and I, both lances ended up in our "personals". Rod was wearing a very period 16th century tilting kit, with full slops and no brayette.
IMHO, a brayette (much as voiders) "completes" a plate armour kit. Yes, you can move in them and they don't restrict your movement and, even if you are wearing a cup, it gives you that one more layer of protection that your Lady is sure to appreciate

.