Usually, Major Vs minor scoring will result in a 5-7% difference in the overall score when shooting around 90-92% of points. The more alphas you shoot the less major scoring matters. The shorter the stage, the more appendix will hurt you. More stages in the 24-30 round range will result in more reloads for you compared to open shooters. A lot of this will come down to stage design. Lets not forget unloaded starts as well.
When skill is equal, open wins every time.