I have the Harmony Wood set of DPN's and the longer nickel plated ones. Although for most projects I use circs, I occasionally use DPN's if only so I don't forget how to use them!
I like the Harmony wood set for doing socks on very fine yarn. The long Nickel plated are wonderful, too, but I find them a bit slippery for really fine wool and tend to use them on thicker more textured yarn where you really need that slide-ability.
Either way you won't go wrong with Knit Picks. Their needles and customer service are first rate!
Good luck and let us know what you decide!