Agreed, can't even put a price on "experimenting", that is where all of your personal preferences will rise & reign supreme eventually! What do you like on that kite right now?, ... what would you prefer IF it could be changed towards a known objective? (for instance: "I want to be able to catch 120s",... that necessitates a killer glide that can penetrate up-wind predictably.)
How much bend in the leading edge construction makes a kite that turns within it's center, but simply WILL NOT rotate on a wing tip? How much stiffness in the leading edge itself prevents that difference from rearing it's ugly head?
If the kite will not back-up it might as well not be a quad at all! Tuning the leaders is merely determining where on the handles that "down" (reverse flight/tricks/absolute control) takes effect.
I have always been a fan of edge binding personally. Take your binding material and fold it in half, (crease that edge HARD, against a piece of glass or with a steel ruler, then fold those two outside edges in towards the middle, then crease it again, finally place that center (folding as you sew or adhering & folding to sew), such that the edge of the sail is captured in between 2 thicknesses of edge binding on each side. Most folks use a triple zig-zag to effect this binding. STRONGLY consider two rows of straight stitches slightly offset from each other instead. Edge binding makes a hard ribbon that slices thru the air when flying in reverse. The better the ribbon is constructed the better/easier the reverse flight becomes. Ah, but there's always the other side,... what is it in this example you ask? Well the great ribbon you've just finished will vibrate at a different level that a single thickness behind it. Those vibrations will create stress fractures and eventually the single thickness immediately next to the edge binding will fail. Does a shortened lifespan of the sail warrant improved flight dynamics? Only your answer matters!
The venting (or holes left open, whatever your solution) along the leading edge "assists" with reverse flight. Do you have to have it? Speed Series Revs don't, they fly backwards almost as fast as a 1.5 will fly forward! Indoor and SUL quads don't need it to fly beautifully in reverse.
How wide and where to locate "said venting" might be fun objectives to consider as experiments. Change only one variable at a time so you can control the experiment,... scientific principle. Four variables and wild oversteer happens, but which one made it the worst or which combination of 2 variables totaled such a profoundly negative impact? Hey maybe you'd like MORE oversteer yet, this is fun! Just change one thing at a time.
Ideally, do this experimenting with a friend, cooperative projects are simply the best!