Why couldn't this kind of mod be used with the previous video's 450nm 90mA laser diode to combine into a single system? If you set the printer for highest resolution, and use staggered laser diodes and a buffer circuit, you could accumulate the print signals for each row, and then on the next row print them as it passes by while accumulating that row's data.
It would only require always making sure you print an extra little bit so the last real row isn't invalidated by the eject.
Best regards, Rick C. Hodgin