It's been a long time since I commented on this subject, which can be found here, [ http://www.revkites....dpost__p__70320
], or go back up to post #29 in this topic. Either way, after considerable flight time, since that post, I'm still sold on the surgical tubing method. Nothing wrong with the O-rings, at all, and several members seem to be having great results with them, although I have heard comments concerning the need for several different sizes, etc, as well as a minor bit if sand intrusion, still being a problem. It's just a matter of personal preference, I suppose, and what you have available.
I fly predominately on sand, and the surgical tubing has worked flawlessly, ever since I started using it. Also, I use the tubing at all six (6) junctions - both ends of the leading edge, and both the top and bottom, of both verticals. Yes, the upper verticals already have factory supplied dust covers, but fine sand can still get in, especially with 2-wraps & race rods.
Again, I've never had a grain of sand, to get into any joint, using the surgical tubing (silicon tubing with a 3/8" OD x 3/16" ID, cut into 1/4" lengths), and now I have it on each end, of each frame section, that goes into an end-cap, and I see no reason to remove it. I leave the tubing on the spars, whether then are in the kite, or not. The tubing is cheap, and you can make up a lot of 1/4" pieces, out of a foot or so. I keep spare sections, already cut to size, along with an end-cap, in a small baggie, in my flight bag. I've never had to replace a piece yet, but I like to be prepared, just in case. Oh, and at home on the workbench, is the place to cut the sections of tubing (with a sharp razor blade), NOT in the field.
As for installation, the dry tubing can be a bit stubborn, to initially slide into the exact position, on the spar, but if you will wet the end of the spar, with a little bit of good "old fashioned spit", the tubing will slide into place easily. Use an end-cap, to push the piece of tubing, onto the spar, just barely short (1/2 mm) of the full depth, and once it dries on the spar, it's rare to have to mess with it again. From then on, when you assemble the kite, the bungees keep the end-caps pressed snuggly against the end of surgical tubing, preventing the entry of the pesky sand................just my 2 cents worth.