I was just being curious on this, I may do them one day but for now my miata is a daily driver. Although i can see the door bars making my hot chick friend have to lift her legs higher to get in, and she has several short skirts she likes to wear.
That is awesome. You should provide photos of said skirt for us to help determine the best doorbar/sea combo for you.
Joking aside, many people swear the door bars combined with a roll bar are great for rigidity. The door bars do mean you are going to have more difficulty fitting an aftermarket seat in there and does give you one more thing to trip over when getting out of the car.
If you aren't tracking the car a lot, I don't think the door bars will be loved long. Track and I both run without them and we try to beat the crap out of little miatas. You may end up hating them and selling them to me for cheap if you only street it.