Danny,
There is a flying 9A based at my home field that doesn't have the slots.
I will probably add them to mine because the skin is stretched very tightly across the roll bar. I'm sure that part of the reason is because my roll bar is about 1/8 inch wider than what is called for in the plans. I tried several different methods to make it narrower, including squeezing it in a large bar clamp, but every time it returned to its original shape. About the time a fellow builder seriously suggested I put it between a block wall and the rear bumper of a car, and put the car in reverse, I decided to just install it "as delivered!" I sure hope the canopy frame is easier to bend than the roll bar.
Mark