It'll look good initially I'm sure, but from a bagmaker perspective;

If it's a simple geometric letting Pat @ PAC do it for you will render the best result guaranteed, more complex pattern, same result, her embroidery/applique will look much finer than any screen print job on a bag flap. If it's uber complex, no problem, Pat has digitized machine embroidery available to her. The only way to get more complex than that is thread painting, more than you'd likely want to spend. All those options will age at the same rate as your bag, screenprinting will fade, flake & go away real quick on nylon