We use the oval instead of the strap when working with heavier pieces. It gives a subtler appearance, the edges catching less light since they aren't square. If we don't have the oval, we'll grind the edges on strap to get that same effect, but it's an awful lot of grinding! The Half-Oval comes in 35" lengths.
Don't forget to pad your brass with Felt or Sueded Polyethylene. You'll find padding here.