In all honesty, before I would spend that kind of money on one of them.. I'd kick a couple hundred more in the pot and go with a custom rifle made to do just what I want. That rifle has a 1-48 twist. Nothing wrong with that mind you, but I want roundball barrels in my traditional or sabot barrels. I own plenty of the 1-48 twist rifles and they are good rifles. Nothing special mind you, just good rifles.
There are too many custom rifle makers out there that are close to that ball field in price. Besides, it is a .50 caliber. If you want a .50 caliber, all fine and good. My tradtional flintlock .50 calibers are roundball shooters or sabot shooters. If they need to do something else, they are .54 caliber.
Did that help? Now order the thing and get it over with.