Pass/Fail

During parent teacher conferences, a teacher whom I highly respect- shared that he had noticed a considerable downturn in my LD son's disposition. There are 2 subjects which he finds particularly challenging: physics and math. He is a junior in high school and despite accomodations, is failing these two courses. This particular teacher told me to investigate having my son switched to a "PASS/FAIL" grading system with these two classes- so that it would not impact his GPA. I asked why I had never been informed of this option in the past and he replied "we just learned about it". Has anyone had experience with this system of "pass/fail" instead of traditional grading system? Thank You!