Laser Engraving - Vector Processing Mode vs Dot Mode

With some kinds of graphics (line art and some fonts) I’m getting excellent results with vector processing mode: very fine lines and faster engraving – the difference in preview is remarkable. The laser sweeps quickly around, rather than punching out dots.
I’m pretty sure it won’t work for grayscale-type subjects (photos, etc.) but it would be interesting to hear about other people’s experience with the limits of vector mode.