I just tried these out. I think the idea is cool, but I found them a little uncomfortable. The grip diameter is slightly smaller than I like and the shape or texture (I'm not sure which is a better word here) was not very comfortable. The little rubber bands hold the needle securely and that part works well. They are quality tubes (as they should be for the price) with no extra little bits of plastic hanging off of them like some of the cheaper tubes. Liners and magnums fit snug in the tube with little to no side to side play. I found it difficult to see the needle with the liner tubes. Also for some reason when I rinsed them, it was tough to get all of the water back out, which I have never noticed with any other tube.
Long story short, I don't want to use them, but now I wish all my tubes had slits cut in them for rubber bands.