In Georgia, the DOT gives each jurisdiction a list of roads where running radar is permissible. Not only must a road be less than a 7% grade, but it must also qualify based on its dips and turns as an eligible road for law enforcement to conduct speed detection checkpoints/run radar. Under the Freedom of Information Act, that information is readily available to the general public if you know where to ask for it. Law enforcement doesn't always respect that list of roads. While there may be an issue with regard to the officer using laser over radar, a qualified attorney in your area can certainly help you explore ways to possibly invalidate the ticket.
As the other attorney mentioned, the speed limit is the same regardless of a hill or not. But in Georgia, there are rules police officers must follow for the results of their radar to be admissible in court. The grade of the highway is one of them. The law is less restrictive on the admissiblity of lasers, which is why most law enforcement agencies use laser today. Check your ticket again. With an attorney, you have a great chance of at least getting this ticket reduced to avoid points, and potentially an argument for outright dismissal. Contact me if I can help.