I would like to question one of your assumptions that passing criteria would remain the same and quality will not be affected...The IITs and IIMs that we are talking about, have a relative grading system (CGPA). If the average standard of the students go down, the passing criteria will simultaneously go down, hence the quality will invariably be affected. Hence in my opinion we need to have a stringent admission process and no compromise should be made with it. I sympathise with the injustice that has been made with SC/ST/OBC over the years and has resulted in keeping them economically backward. Hence I would advocate to provide them financial support for their higher education, rather then providing them direct reservation.