Those are quite interesting, thanks for sharing. I do like the look of the join, but, I, too would be afraid of a residue. But, I guess you will let us know about that as you knit
You know, far eastern knitters are masters! They create such beautiful knitwear! I wonder if this is the type needles that they normally use?! As for a good size and length, personally my fave knitting needles are sizes 6-8 and 24" length tip to tip needles.
Please keep us posted.