The 4.9 system is an old one which I have had on the 4.9, a paper Tiger and a Tiger Shark. These all worked very well and the only reason they jam is not using them properly. Jams are usually fixed by simply pulling harder. THis system is great and I am investigating doing to my 14 squared. I may us a flat web but the theory is the same.
Rope system can work very well for up and down in concert with a bungy to create tension.