I've used 70% and I think 85(?)% shadecloth for various things including shading a run. It is WONDERFUL stuff. If installed vertically or at an angle you will actually get much more shading than its official percentage says (that's measured with it at right angles to the sun's rays).
Some rain will blow thru it, yes, but a whole lot less than if it weren't there, and what blows in is mainly a fine spray rather than big drops. I have a couple large nearly-vertical panels shading my west-facing sliding glass doors, and we get some fierce thunderstorms from the west, and hardly ever does the glass of the doors get so wet that you can't see real easily through it nor the deck behind the shadecloth get wet enough to 'look' wet.
The very best thing about shadecloth vs tarps though is that it does not flap much in the wind, assuming all sides are fixed. With a tarp, no matter how tightly you try to stretch it or how many ropes you crisscross over it, it will still naturally 'want' to flap and thrash in the wind, which leads to premature destruction of the tarp and if it's attached too tight to something too weak it can actually demolish the structure it's attached to. Shadecloth doesn't do that. This is a great virtue in areas with big storms IMO.
Good luck, have fun,
Pat