**YAWN** Q-power 600lb **YAWN**. Next question....
Depending on the safety line q-power may or may not fit through the flag out. I seem to remember that the north 5th element trust bar has a long thick line that goes up to the proper 5th line so you can use q-powerline on all 5 lines. Most control bars can not use q-powerline because they are now mostly single center flagging and the q-powerline won't fit through the safety flagout mechanism (because q-powerline has to be knotted or sleeved and can not be spliced, and the safety on most modern control bars only has room for a spliced line to go through).
Be careful about blindly recommending q-powerline, fewer and fewer control bar systems can use it because of how the modern safety features work.
In this case though I think q-powerline will work. Check out how your safety system works, make sure it doesn't require a spliced line. If it doesn't then you can use q-powerline.
When I use q-powerline I like using knots, to create loops and then add pigtails on the end with a knot or loop accordingly. I have sleeved q-powerline before but I quit doing it, the knots (unlike 12 strand line) work fine.
When I need a new line set I buy some dyneema or spectra (costs about $100 retail for the line itself) and splice the lines then pigtails, using a simple class 1 splice with a lock stitch or zacher's knot if it doesn't have to go through a safety.
Those chinese lines look fine to me, but like you said I think the 5th element trust might have some funny line lengths you have to worry about and I also haven't seen chinese lines with a 5th line they are always 4 line sets. If you are recutting lines you might as well buy raw line and learn how to splice.