Hi Alberto, Welcome to IceInSpace!
Those are some amazing DMK deep-space images, just beautiful. Probably the best i've seen from a DMK.
Why do you want to get a DBK? The DMK is much more sensitive as you'd know, because of the bayer filter. Can you not get a filter-wheel and colour filters for your DMK31?
Then you can use it for RGB planetary imaging as well as RGB deep-space imaging.