You should take the August flex if you feel confident. Meaning: If you are scoring consistently high in those 4 exams you have taken, then go for it. However, let's say you got a 155 and then 170 and then a 151 again, I'd say you aren't ready. (4 tests are usually not a good enough indication) Also, many "LSAT pros" mostly never recommend cancelling LSAT scores. It doesn't matter if they see your cancellation or low score. They will only consider your highest score.