Thank you Derek, Allan and Ciarlotto, I appreciate your comments.
So far I haven’t noticed a “game changing” difference between my DMK31AF04 and the ASI120MM in terms of image quality, but my sample size is only one solar imaging session!
What I did notice is that flecks of the red aluminium anodizing kept appearing on the screw threads of the 1 ¼ inch eyepiece adapter, so I mated and unmated these several times and cleaned the parts to minimise the potential of debris landing on the chip window.
One of the main reasons for acquiring the ZWO ASI120MM was that I needed to move from my DMK Firewire units to a USB camera. Of course, the price was very attractive!
Cheers
Dennis