It looks to me like the pattern has several peninsulas that aren't supported by much. This is where BB ply shines. You could get away with thinner BB ply than you could using solid hard wood. Those kinds of places, especially if they are cross grain, are much more prone to breakage in hardwood. You would need to compensate by going thicker, which to me, detracts from the piece. I think this kind of scrolling benefits from using thin stock. 1/4" would the thickest I would go, but that's my personal preference. As for jagged edges, that is as much or more a function of blade choice as it is the material being cut. Since this pattern employs a lot of straight lines, sharp corners and geometric shapes, it doesn't lend itself as readily to using a spiral blade. But, that said, a combination of the right spirals and straight blades should make this turn out nicely.