I did not like (so I did not use it) my QA1 extended low friction ball joint. I had about .005" play in the ball axially, had no boot on it to keep debris out of the grease, and had no adjustable seat to take up the play that I measured. Yes, it was low (no) friction, but I didn't like the idea of a brand new ball joint being no better than a worn out one. Questions regarding the play, to the vendor, was "that's how they make it low friction".
My second choice, which I like and did use was the AFCO low friction extended ball joint, which is a more accurate description of the friction level, and it does have a boot, with no play in the ball.
I guess for a strictly racing application, the boot is not as important.