I play with fairly low sens (1150 dpi, 0.49 ingame scale). I don't see any reason you should use high DPI unless you really believe in forcing kills with crazy inverse feints. Why? I can count the amount of people I cannot outlast with the most basic-b*tch feints on one hand, meaning, fundamentals (blocking, timing, distance) are a lot more important than cranking out some wild feints. Don't let anyone tell you otherwise. Lower sens will make the mastery of clean and consistent blocking a lot easier.
Just my opinion.