I have been admiring and praising the Hya-Hya DPN for knitting softer spun yarns on the basis of some hand knitting at a show. These are very light weight knitting needles made from stainless steel by fusing the tips on to tubing. Recently I bought a bunch of them and it turns out that for use with a knitting sheath sizes US#1 and larger sometimes tubing crimps and collapses suddenly unless the knitting sheath fits them just perfectly. used very gently, and they will likely work very well, but I am an agressive knitter and they lasted seconds.However, minor wear in the knitting sheath can result in such loss of perfection. Their #0 and smaller needles are solid stainless steel, which does not crumple like that larger needles but does not have much spring and bends rather than flexing.
The Signature needles have that fine point so beloved of fast knitters of tightly spun yarn. Again in sizes above #0, the needles are made by fusing aluminum tips to tubing. Again localized pressure on the shaft of the needle can result in fatal (to the needle) crumples. Moreove, Signature needles do NOT like being stepped on. Knit VERY gently if you must use your Signature needles with a knitting sheath, and I do think you will be OK. Signature’s needles in sizes #0 (and smaller) are made of a very high quality stainless steel, and are not real “springy”, they may bend on you in knitting sheath use. Still they are beautiful needles made by very nice people.
My needles just are not as pretty. On the other hand my needles have more spring, and there is nothing that your or your kid or your horse can do to damage the needles that I make (except leaving them in the damp so that they rust.) Take the above with a grain of salt, because I bend my spring steel needles all the time. I bend them and they keep on working. Hya-Hya and Signature do not keep working if they get bent.