Spirals are a great option but should not the only blade in your arsenal. They do not have the crisp, straight, clean cut of a flat blade, and are lousy for cutting a crisp font, but for portrait work or cutting a line drawing they are hard to beat, or for cutting patterns that are too big to turn in your saw. I really like the look of a spiral for cutting line drawings like cartoons (Peanuts drawings come out great), coloring book patterns, or to get a heavier line for veining.
You can order a set of Flying Dutchman blades from
Mike and mix the sizes in a class to pay the half- or full-gross price.
The ornament on the left was cut 100% with a #5 new spiral. On the right, an FD-UR#9 was used for all cuts except the outline of the pinky finger (these were test cuts). The spiral gives a heavier cut. #5 will fit through a 1/16" pilot hole. This is a 3.5" tall ornament that would be seen from a distance, so heavier veining is a good thing.