If I understand DougHobie17 correctly the line coming out of the furler goes through the block, and is tied to the bridle (i.e. under the furler). There is another line attached to the becket of the block, and this line goes to a cleat on the cross bar.
I haven't tried this yet, but this system would simply allow you to furl the jib faster (i.e. one inch pull on the line attached to the becket corresponds to two inches on the furling line). However, I fail to see how this would help prevent the furling line from getting tangled when it gets loose.
I've had this problem on every boat from my current Getaway to a Peterson 44' I use to own. If you don't keep tension on the furling line, you're about guaranteed to get a jam in the furler. And a jamed furling line on a 44' cruising boat when you'r trying to reduce sail in a storm is no fun
Here are other ideas I toyed with on the Getaway. My first idea was to re-route the furling line (from its current straight shot from the furler to the crossbar) such that it would first go through a small block on the port hull bow, then back to a cleat further aft on the port hull (near the middle crossbar).
However, one factor to consider is that the angle the line comes out of the furler must be such that it doesn't rub on anything. As I routed the line to the side toward my bow block, it chaffed against the edges of the opening in the furler housing. Then I had no furling line at all
At this point, I'm trying to figure out how I can modify the furler housing so that the opening points to port. Haven't found the right answer yet, but I love these projects, and when I find a solution I'll post it.