In our State the only way you could use the Savage is by loading black powder during our muzzleloader season. Whether or not you should buy it is a personal decision. Needing the rifle is not the question. Wanting the rifle is the question. If you want it and the cost of the rifle and all the new gear needed to shoot it is not a problem, then get it.
I own numerous muzzleloaders. Do I need them? No.. but they are fun to have because I really enjoy taking them out and shooting them, whether hunting or target shooting.
As for accuracy, the Savage will shoot as good as you are. I am sure if your old one is accurate like you say, you might not really see all that much improvement in accuracy over the Savage. I have a CVA Staghorn and it is a very accurate rifle. I also have T/C and a Knight. They also are accurate.
From all I have heard, they are a beautiful well balanced, accurate rifle. I am sure if you got it and then changed you mind you could always sell it for near what you have invested in it. I personally am one of these people that once I own a rifle it is mine forever.