Re: who can wear hakama
Another reason to ask whether or not to wear a hakama when visiting, at least if you are mudansha: it can be a safety issue. Those you're training with, not knowing you, may make certain assumptions about your ability to take ukemi based on those "black pantaloons" you're wearing, depending on the customs of their own dojo. It's not ideal, but it happens. Most of us at least sometimes will make those sorts of assumptions, whether it's about the stranger in the hakama, the stranger in the gi with right lapel over left and obi hanging down to the floor, or the stranger in the sweat suit.
Of course, if you _really_ want to wear that hakama, then you can safely lower peoples' expectations of your ability level by taking special care to trip over the hem (as spectacularly as possible) when getting up for the first technique. ;-)