I'm not very sure what the advantage is, honestly. You trade a smooth outer surface that can't catch or jam for the convenience of. . . not having to clip off a double ender? (And unless your line ends up precisely where you want it, it seems to me you're going to have to use a double-ender to keep the line from unspooling further, anyway.)
I'll be interested in the reviews, but this looks like an equipment solution to a non-problem to me.
It can't unspool further once it is "cookied" onto the jump line you just installed, because it can't turn.