I stopped by a few months ago, on our way back from vacation. Definitely Worth a stop if relatively near, but would not go that far out of the way if looking exclusively for southern items. Do remember a decent amount of Southern stuff, but not an overwhelming amount. Picked up an Railking 4 bay cylindrical hopper with Southern, Big John on it.
I was more impressed with the amount of track and accessories he had in stock. Lots of new, old stock buildings and plenty of Lionel and MTH track. If I was building a layout from scratch, I would send him an item list and give him a chance to give a group price.