I think the main difference between 1500V DC and 25kV AC is how close the climber would get before being zapped
Some train accidents over here have occured when somebody would manage to climb onto the roof of a car. They didn't realize that there isn't much clearance between the roof of the train and the underside of a bridge. Plus, the rod part that touches the overhead cables (aw, what is that thing called!!??) has a spring so it can adjust accordingly...