Signal being data and not clipping blacks, I've always dithered and use the required darks, flats and so on. Your high guide numbers would reduce your detail as well, I did some 600 sec subs on pterodactyl which great star shape across the field, i just wish I figured the filter/ reducer before I started it
I saw your M83 and reminded me when I use to live in bortle 2, I just wish I had the camera and filters I have now.