i have that flat style for my pool, provided by the pool installer. my first one tore before the first summer was out and i'm on the second one now. the first tore when i first powered on the pump to backwash the pool filter and it wasn't completely straight (so it was enough of a kink that the pressure overpowered the seam). However, it had been out all summer, not protected from the sun or elements, etc. Also, annoying to roll up.
If you go with that variety, i would go with something thicker/more durable.
If you go with that variety, i would go with something thicker/more durable.