Despite there being lots of reviews that say the Knitpicks Options interchangeable needles are lacking in quality control, due to some join issues, I love these needles. I bought the set of Harmony's last year, and have been using them non stop since.
I have never had any issues with the joins coming undone, and yes, it DOES help to remember to use the key to tighten them completely. None of the male parts have been stripped so that they are not functional.
I love the smooth join on these needles, and feel that the points are better made than even Addi Lace. Those of us who do lacework or knit through the back loops understand just how important pointy needles can be.
My only complaint so far is that the cord lengths are limited, but nothing that a little creativity can't fix. I liked the idea of the Denise interchangeables having the links that you could connect two cords together to get a correct length, but hated those needles with a passion. The Knitpicks needles are of a better quality, and also seem to last longer, so lack of cord options would not prevent me from recommending them to EVERYONE in the knitting community.
Now if only I had the money to buy the set of original Options....