I'll be glad to contribute another tip (it works with Boye's set, I'm not so sure it'd work with Denise's because of the shape of their needle tips).
Because of their almost symetrical shape I use Boye's needle tips to knit I-cord. It works perfectly. No need for DPNs sets in every single size just for I-cord.
I'd like to thank you for your great site. Except for knit and purl which I learned when I was 7, I have learned almost everything else from your site in the past months. I only understand 3-D; if it wasn't for your videos I wouldn't be knitting now. Thanks again, Amy.