Interior fresh air doors...and Go!

Hello FABO Family, I have a question, and am looking for opinions for and against.
My car is a 71 Duster. It has been apart for more years than it was together under my care. I may have driven about a 1000 miles if that.
My question: what have all of you done with your fresh air boxes under the dash? How many of you that have modded your cars, still have them? Who has gotten rid of them, and why?

It seems to me, I remember the airflow I got from them wasn't all that great, and I had plenty of crap blown into my car through them, maybe even some water leaks.
Some of you guys may have them and love them... I wanna hear why?

So I guess I am looking for compelling opinions to sway me either way.