I would nail knot a perfection loop on to your fly line. I watched one of the biggest smallmouths I ever caught swim away with my fly and leader using those braided loops that slip over the line. Will never use them again.
There are a couple of secrets to using braided loops to ensure that won't happen:
Buy the
Rio versions, they are sized, have a longer junction and don't require heat shrink tubing.
Clean the end of you fly line thoroughly before installing the loop, old line floatants or shooting treatments make the line slicker.
IF you cut the very end of your fly line off on an angle, it goes in easier and further up the braid.
Work the fly line all the way to where the loop is actually formed in the braid and up past the part of the braid that forms the loop if you can.
Work a tiny amount of UV Knot Sense into the braid at that loop junction to keep the loop from ever pulling apart.
If you don't like the slip-on rubber sleeve Rio uses in lieu of heat shrink like the Cortland loops use, try heat shrink instead OR wrap thread over the back end of the braided portion and coat with UV Knot Sense OR just use Knot Sense and skip the thread.
If you want to use heat shrink, invest in a cheapo hair straightening flat iron
like this from your favorite retailer. They work fantastic for shrinking heat shrink tubing and are way less risky on your fly line versus a lighter.
I have been using loops installed this way for years and have zero issues and non existent hinging because I push the fly line so far up the sleeve.
Good luck whatever you do!