My husband (then boyfriend) bought me a set of Boye interchangeable circular needles when we were still in college--a big investment at the time. And I've been using them ever since (*cough* 20+ years). I love them, and have certainly gotten my money's worth out of them. I've been thinking of replacing them, either with the Denise needles or with Knitpick's wooden needles, only because it's getting increasingly difficult for me to buy replacement parts (the dog has chewed up a few of the cords, for example). But I love always having my needles in this one, tidy case. And I've also done the occasional pattern where I screw one size needle on one end, and a different one on the other, for a cool effect.
Anyway, I think interchangeable circulars are a terrific investment. I never knit with straights because these are so darn handy.
Hope that helps!
Becky
