Has anyone ever used the Universal clip-draw? I want to give it a try on my KHAR cw9. I am just worried about if it would cause any problem with the function of the firearm. I do not want to put it on than have to take it right back off, but if I do will it leave marks on my stainless slide?

Please let me know anything else about them as well, Ive already searched and havent found anything. Thanks.

I have one on a Kahr P40 Covert.  Works well, still fits into its Nemesis pocket holster and Sparks Summer Special IWB holster.
Does not interfere with functioning at all, but interferes just a little with handling –– the spring is powerful on that little gun, and it's hard enough to retract the slide as it is.  The clip interferes with getting a strong grip on the slide.  TapRackBang is not going to be a fast operation.  Loading/unloading the chamber takes some finger strength, and you better be very careful about muzzle direction and trigger finger position when you are doing all that vigorous slide-yanking.  IMO, though, it's worth it; a useful addition to the gun.

Thank you very much, I agree with you about the strength of the spring. I think Ill put it on, with my Galco Stow and Go I need to wear a large t shirt or a hoodie to ccw. Hopefully with this clipdraw I can ccw with a medium shirt and cargo shorts, at least in the summer and spring.