I contacted Vortex and they said it depends. They are not really equipped to change reticles and if they screw up the scope changing the reticle, they give you another scope. It will be a used scope that they check out as good to go. You may have sent them a brand new-in-box scope and get a repaired one in return. The charge for the swap is $69.
When I mentioned Viper scope, they asked if it was a closeout model or not. They did not want to have people buying a closeout model and for $69 get a Mil-Dot when they are charging $400 for the same scope.