This topic has been beaten to death I'm sure, but I just wanted to share my initial thoughts regarding the QHY 268M camera. I received it in March and have had the opportunity to do some narrowband imaging from home and broadband imaging this month from a local dark site. Coming from an ASI1600mm-Pro, the difference between the cameras is quite noticeable - both in terms of physical stature and performance.
Here is a side-by-side comparison of a single, uncalibrated sub of the Horsehead Nebula. Both 5 minute exposures using a Chroma 5nm ha filter. ASI1600 on the left (with old scope at f/6.5) and 268M on the right (current scope at f/5.1). ASI1600 at 200 gain/50 offset and 268M at 56 gain/25 offset
Autostretched (using ASI1600 STF on both): https://imgur.com/a/zgDtexk
As you can see, the increased FWC of the 268M (really, IMX571) is quite staggering as fewer pixels are clipped even when using a faster focal ratio.
1:1 on both images (each with their own STF applied): https://imgur.com/a/WgUWaJ9
This is obviously not a super in-depth comparison with quantification of means/medians/what have you. But from just a "to the eye" perspective, the new generation of sensors is appearing to be one of the best improvements to amateur AP ever since CMOS technology has taken the torch over the past few years. Very excited to continue using this camera and see what it can bring to the table.