my first q set lasted over 7 years of regular use--still in good shape when sold with a kite. q line will break at a knot--use double overhand knot/figure eight and breakage won't happen.
This is key guys. I tested 4 or 5 times and line breaks if you use normal knots ('Granny knots'). MUST imperatively use 'Double-figure-of-eight' loops, then it's all good.
I work at a chemical plant and I'm a member of our fire and rescue team. I do deal with a lot of knots so I was using a figure 8 on a bite. I'm not sure if your referring to this as a double 8. A double 8 on a bite has 2 loops coming out of the knot if I remember correctly. It is not a very practical knot so I never wasted the brain cells on memorizing it.
What would be interesting is to get a solid test on knot efficiency for kite lines with various knots. On most ropes a figure 8 is anywhere from 70-80% efficient. Rope diameter does effect the efficiency so my guess would be on the low end or even lower.