I now use a small dyneema loop I spliced. It took me while to get the damn thing right. It has a sliding eye on one side which is closing up under load, and a turk knot variation on the other side to get through the eye. Like the attached image (sourced on the net, mine is not that neat!)
Very cool... the one in the image doesn't appear to have a lock stitch.. i take it you add a lock stitch?
There is no lock stitch. You need the eye to slide. When pressure is applied on the loop the eye closes locking the knot in place. To open or close the loop you just slide the eye open and push the knot through, and you can only do that when there is no tension on the loop.
It's a simple bury, the outside is bunched up a little so when pressure is applied the inside slides and close the eye. The knot is done with the two end of the line still inside each other. At the center of the turk knot there is a stopper knot made at the end of the lines. There is no need for a lock stitch anywhere, the turk knot acts as the lock stich.
Now that I know how it's done I need to take measurements to make it right everytime: judging how much line you need to do a turk knot is hard!
