Yes , Im using gbrl. And yes I am using laser gbrl software. But unfortunetşy lasergbrl doesnt convert images to gcode like yours. And the other softwares creating gcode point to point..There isnt lines. Just dots.
Buy the way your sofftware output files working fine with GRBL. But only issue is like i said , S command. I think im not the only one having this issue.
I hope , you will give the solution for us.
I think its just adding min and max levels with S value. If i type 255 , max is S255. If i type 2000 , max is S2000.
I cant find any "alternatives" equal your final file quality.