Recently, I said some bad things about bamboo needles. I must apologize. The SPN bamboo that came in this morning had a nice finish on them. I cut them down, and trimmed them into nice 12.5" bamboo DPN. Then, I drilled out a knitting sheath to fit these US size 5 needles, and now I have a knitting system that will knit to Meg Swanson's gauge of 5 spi with worsted weight wool. Yes, I have Addi Turbo circulars in size 5, but a knitting sheath with long DPN gives me the leverage to knit faster with less stress on my hands and wrists.
One other thing, my knitting is more uniform and my tension is more consistent when I knit with a knitting sheath. It is counter intuitive that my hand-made needles with all their imperfections should allow me to knit better than I can knit with my perfect Addi Turbos. I am sure that there are knitters out there that produce better quality knitting without using a knitting sheath than I do using a knitting sheath, but using a knitting sheath allows me to produce a higher quality fabric. That is my observation on the swatches that I have knit on sizes 1 & 3 needles. I have not done comparisons on larger needles yet, although the gauge swatch that I did today on those new bamboo DPN looks pretty good.
I have seen some comments to the effect that some of the perfection of old knit objects is a result of them having been worn and washed so often. I suspect the use of knitting sheaths contributed to the perfection of those old knit objects.
Aaron