I think you need more stretch than Amsteel. We certainly do, because our reef pints are designed to raise the boom each reef. This means that the height of the boom varies. If we drop sail when the boom is high, the lazyjacks have to stretch a bit. We use 5/16" Dacron on our 66 foot mast, terminated at about 44 ft up.
Four legs (17 ft boom)
We also have an integrated sailbag that we call the lazybag. It is supported by the lazyjacks when the sail is furled, and lives rolled up along the boom while sailing.
Works very well
We experimented a bit to get lazyjack lengths right to haul up OK, and to stow against the mast when hoisting sail and while sailing. We started plenty long, then fiddled with bowline lengths till it was right, then took it all down and tidied up with whipped ends etc. Splices would have been neater, but we have not got to that.

Lazyjacks are great for short handed sailing, specially with the lazybag.