Hi Alberto and welcome,
There is a significant difference between the two. Monochrome vs OSC, the Monochrome camera will always come out on top.
I've seen both DMK and DBK images side by side and the DMK images easily had the most depth and detail. I'm not saying that OSC wont produce great results but when comparing the two the Mono camera is superior.
I agree with Mike, you should look into getting some RGB filters to use with your DMK31.
My 2 cents...
P.S. Your test images are amazing, well done.