Same as most; I use it as a reference when moving around in magnified view and I find it very useful for that.
Hereās one more vote to keep it, I find it useful sometimes. Adding an option to toggle it would be fine too.
I do too use preview and like it when I find it useful. I donāt use it constantly, so for me it COULD be made invisible.
Also in add RGB parade and vectorscope as histogram alternatives Ā· Issue #4149 Ā· darktable-org/darktable Ā· GitHub I mentioned that in some cases Iād love to be able to have histogram on the leftside of the window where preview is instead of previewā¦
I could also be totally fine with detaching preview and itās zoom navigation functionality to preview window on 2nd screenā¦ and have histogram(s) as well on 2nd screen 
sounds interesting