So from an RTO point of view, is the somewhat longer runway helping me with the derated thrust and different flap setting?
Yes.
The ATM method calculates an accelerate stop distance within the Runway length available (& often shows a very small stop margin). Provided the real OAT is less than the assumed temperature, then your indicated V1 will occur at a lower TAS (hence lower ground speed) than calculated. Therefore you will be rejecting the take off from a lower ground speed and have considerably more stop margin than the calculations suggest.