I used thin dyneema in one length inside the jibs and mains luffs of my SJR. It goes inside the tiny hem, and runs in one length through all the battens (actually, my battens are two parts, one each side anyway). I threw a few stitches in here and there along the luffs, and simply belayed the one piece bolt rope at the yard and at the boom. No eye splice, just a couple of turns and a hitch.
I used dyneema, not so much for strength, but I wanted something as thin as possible which I was sure would not stretch. Nylon stretches a bit, doesn't it?
I think it is a nice thing on a SJR to have nice straight luffs and by making sure that the bolt rope on the mains is about the same length as the boltrope on the jibs, and it stays that way, you achieve that straight jibs luff nicely by tensioning up with the running parrel downhauls, which work so well on that Amiina rig. The running downhauls tension against the halyard.
The downward force on the downhauls need not be great - just tweak firm with one hand and belay. (Not "twang tight" like the bermuda jib luff needs to be). So I don't think the bolt rope needs to be incredibly strong, but if the relative length of the two boltropes (mains and jibs) gets significantly out of whack because of stretching, then that convenient little adjustment might not work so well as it does.
(Actually, I think my mains bolt rope might be a smidgeon long, but the battens are flexible enough to bend slightly under the very moderate load of the downhauls. The result is, the parrel down hauls whose spans put a little bit of downward tension onto each of the battens, makes the jibs luff satisfyingly straight under very, very moderate tension).
The luff "entry" of the jibs, with that slim boltrope, is better than webbing or a heavy tabling on a SJR. (I imagine that, anyway). I like a nice tabling for the leech, but a bolt rope is justified on the jibs luff since it is completely out of the way of the mast, and the jibs entry is carefully made to be as aerodynamic as possible, since that's part of the reason for having them, isn't it?. It might not make a lot of difference, but it's all good fun and just as easy as a webbing or tabling, so why not?