I operate mostly short sectors with B737, so we're light weight. De-icing pad is located at the deep end of the runway which is 3600 m. Snow clearing/chemical treatment of the runway often brings the runway conditon code up to 5 (= Braking Action Good). Performance Tool publishes our accelerate stop distance and stop margin in case of RTO at V1. Since the runway is "contaminated" we're confined to using Derate and no ATM. It's definitely annoying to see TO-2 (Derate) with stop margin of 2000+ m when we safely could've used TO-2 and ATM 59 deg. with a stop margin still well in excess of 1000 m.