Just in case you have never used CMOS and have been using CCD like the rest of us for the last million years then let me tell you it requires a different approach, you can forget long subs as the are not needed and at most times detrimental to your image quality. Allowing for CMOS’s sensitivity, higher dynamic range and super low read noise broadband imaging typically 30/60s and 120s is more than ample enough for narrowband, you just needs a lot more of them of course.
The ZWO ASI-2600MC Pro Colour CMOS is one of Sony's new generation zero ampglow sensors, so no need to worry on that count :)
This camera is set to Unity Gain as our default, if you have any special gain and offset requirements for CMOS imaging please discuss and we will do our best to accommodate you.