Reduced load depends on the school. We have looked at a number of schools ranging from NESCAC Schools, other LACS, to research universities. For a student who wants to be considered a full-time student, it usually means one class less than the normal load, but one that meets the full-time student requirement.
Some colleges also have a school of general studies, or something similar, which allows the student to enter on a part time schedule, at a reduced tuition rate. Out son has a huge gap between his cognitive ability and processing speed, and tends to pick everything on the challenging courseload menu. He also has a fine motor issue that puts his handwriting and keyboard speed in the 5th percentile (95% of students are faster than he is at those tasks). So, he will need extra time for tests in college. For his college transition, we are encouraging a reduced load in a challenging environment, because we think that is best for him. This may mean that he will take some summer school courses or end up on a five year plan.
This may not be the best for every student, but it is looking like the best option for our son.