It's the same actual DOS WC3 files in both versions, so differences in deadzone and graphical scaling sounds like a matter of DOSBox config settings. Some info on that https://www.dosbox.com/wiki/Dosbox.conf
I just installed WC3 GOG version and its running fine exept for one thing and that is my joystick seams to have a big deadzone and movement seams to be a bit rough and unprecice.
I have a Thrustmaster T16000M. Does anyone have an idea how to make it work more smooth?
I installed the Origin version and it ran smoother. After taking the values from that version my GOG version runs also smoother but it dosn't look as good. More pixelated but at least I can aim better now.