The open-source cytometer team has been acquiring image series where the Raspberry Pi 3 GPIO controls the LED on/off cycling vs. the Basler Dart camera. It is apparent that the Basler Pylon 5 SDK waits to release GIL until the Basler Dart exposure AND the image readout is complete. This means using a single-threaded Python script, the LED will stay on as much as 350 ms after a 1000 ms exposure. This is probably short enough to not worry about bleaching the fluorophores.
Next up is to build real LED Engin-based illuminators, selected for the proper illumination wavelength.