I know nothing about Delrin Nuts.
Are they strong? Will they wear out fast on a CNC?
Why use them? Back lash?

ANYONE GOT INFO OR USE THIS TYPE ON THERE MINI MILL?

I don't have any delrin nuts, but I did thread some to capture my ball nuts in and lock them to the steel flange.
Delrin is some really nice material. It is hard and does not wear very fast. It has it's own lubrication somehow. Just fairly slick stuff. It machines well also.

Take a look here.
http://www.dumpstercnc.com/leadnuts.html
Contact them and they should be able to give you all the specifics you might want to know about wear.
Many of the guys here have used these Dumpster nuts.

Thanks for the info LeeWay.

Yes, delrin has phenominal wear characteristics. It's not as strong as bronze, but should be strong enough for a small mill application. My only concern is if you're using delrin as an exact replacement on an X2 mill for the existing nut, the delrin may flex a bit.