Chris, just out of curiosity, have you used one of the ZWO or QHY CMOS cameras? Namely the ASI1600 or QHY163? If you actually take a look at the driver, up front there are just two sliders. Gain and offset. The manufacturer did provide a handful of presets…usually a maximum DR, unity and minimum read noise preset. There are offsets preconfigured for those settings…however, many of us have done testing and determined that other gain settings are more optimal. Those custom gain settings do not have preset offsets.
For the record as well…I am not sure that the default offsets in the presets are always most optimal. I’ve had clipped black pixels (well, due to how the driver scales 12-bit data into 16-bit, they end up as a value of 1, rather than 0) at unity gain and the minimum read noise presets. It’s a tough balancing act at higher gain with these cameras. On the one hand, you want to increase offset to eliminate any and all black clipping, however on the other hand, the more you increase the offset the more you eat into dynamic range and risk clipping stars.
In some ways, having a small number of clipped black pixels is preferable to clipping stars, since with dithering and sigma clipping you can easily reject those outlier noise pixels. However…clipped stars are clipped stars, as once you clip noise drops to zero, and you are aligning on the stars as well. So a clipped star is always a clipped star, there are no processing techniques that could resolve that…not like clipped black pixels anyway.
I think there are reasons to use offset as a means of optimizing results for the optical system and skies. In my case, I tend to need to keep my offset low and I compromise with some black pixels. Someone with a slower, high resolution optical system and darker skies could certainly increase the offset and avoid all clipping, as they might not use up all the available dynamic range anyway. When you get down to it, and fully optimize the gain and offset for your particular setup, I think you will find that more often than not, you are using a custom gain and offset setting, rather than one of the very few preconfigured ones…so just letting the manufacturer take care of offset for you is not really an option.
Oh, one other thing to keep in mind with modern CMOS cameras. They can easily do double duty as both DSO (deep sky) and SSO (solar system) imaging. Many of us do indeed use these cameras for both purposes. Readout speed on these CMOS cameras, thanks to the fabrication technology and support for ROI (region of interest, a way of reading out only a configured area of the sensor), is extremely high (hundreds of FPS) while maintaining the low read noise. The freely variable gain is quite useful with planetary imaging, and you can often use a higher offset than the defaults (if there is one) to ensure you don’t clip any pixels to black, since you don’t often need 12 stops of dynamic range with planetary.