One thing I am puzzled about is why according to your analysis cooling makes no difference to SNR for exposures less than 100s for the ZWO. Jim, why do you think that is?
Although having said that the overall difference in SNR seems negligible. Should make no difference in EAA or traditional astro photography.
I would love to test the MC camera - maybe Rock can provide one for independent testing?
Good question regarding the SNR not responding much to cooling on the ASI294. My guess is that at lower exposure times the noise is dominated by sources that are not sensitive to sensor temperature. It is only after the exposure time gets longer that temperature dependent noise sources become more important and thus cooling shows a larger impact. Based on your experience, can you think of any sources of noise that are not strongly dependent on sensor temperature? Shot noise, but what else?
Of course there is a whole other possible reason why the observed SNR does not improve dramatically with cooling at lower exposure times, and that is what is the actual sensor temp versus the reported sensor temperature. At shorter exposure times, because the sensor is operating at a higher duty cycle, the heat production rate is higher. So even though the sensor temp reading says it is being cooled, maybe at short exposure times it is actually significantly warmer than at longer exposure times. Does that make sense? This is pretty speculative, and I am not sure how we could confirm it without taking a camera apart and installing all sorts of temperature sensors.