And had Jack not sacrificed his grandson the 456 would have either taken millions upon millions of children, or wiped out the planet. OK it doesn't equal the Dalek's getting Time Lord tech, but it's a pretty damn big thing.^In fairness me I killed my own people to defeat the Daleks probably doesn't have much in the way of high ground on this!
To a point... On the other hand, the Doctor would not be wrong to note that had he not blown up Gallifrey to destroy the Daleks, it seems (based on dialogue from "The Sound of Drums") that the Daleks would likely have exterminated the Time Lords and gained access to Time Lord technology.