The "Tempered" only means that the finished surface is slightly more resistant to scratching, but it bends just as easily as the regular variety. Use the regular stuff, as it is cheaper. If you buy it in a 4'x8' sheet, you can cut it with a plywood or panelling blade in a Skilsaw, but be sure to work from the back (rough) side, as the motion of the blade will cause some minor fraying along the cut. You can form this down to about an 8" radius.
It's also good for "coving" the corners of your backdrop, if you plan ahead when finishing the room. Simply use 1/2" drywall to cover the studs, except at the last spacing from both sides of the corners of the room. Here, use 3/8 drywall, then cut a suitable width of Masonite that can be curved, then "popped" into the corner. The edges of the 1/2" material will hold it in place, although it's still best to also drill and countersink the edges for drywall screws, and apply drywall tape as you would elsewhere.
It works for both inside:
...and outside corners:
On inside corners, the Masonite should be somewhat narrower than the total width of the two stud-spacings, while on outside corners, it should be considerably longer, but in both cases, cut and fit to suit.
Wayne