I bought some twisted tornado crimps yesterday at the Bead Mercantile Show, and I've actually managed to make two necklaces today that I've used them on.
They are different from standard crimp tubes in that they have a twist (duh) in them and in that you don't use crimp pliers with them. You just smush them all flat with your chain nose pliers, and they turn into a nice rectangle with a bit of a pattern. In theory the twist makes them hold better.
I've only used them with .14 21 strand Softflex, but I do like them for that. I'd had trouble with crimp tubes holding on that size Softflex and this does seem more secure. They do take a LOT of hand strength though.
Random comment overhead at the bead show yesterday from a bemused husband following his wife around: "Do they make beads without holes in them?"
Elise