Meh, a lot of it seems to be on SDC's end right now though with how much infrastructure they seem to be working on. DW had a lot of buildup at various points as well when they had to rebuild their parking, cut through a massive hillside, and get a lot of groundwork in place for their expansions.
DW will still be the emphasis for the chain into the near future, but SDC certainly hasn't been forgotten about. They could have opened the new coaster in 2017 if they wanted, but it seems to me like it's disorganization at the park leadership level that's holding them back. Seems like there is a log jam of things that SDC desperately needs to work on and they keep switching priorities, at least from an outside perspective.
And as always, you invest where you think your money has the most potential for growth. Branson is doing better than projected, but Dollywood still has the edge.