I think that the crowd intangibles are overrated, especially for experienced teams. Elite players, such as MJ, Kobe, LBJ etc. seem to even feed off of an opposing crowd's negativity as much, if not more than their homecourt crowd's support. As long as you've got a packed building, I think that both teams can feed off of the energy in one way or another.
The biggest home advantage in sports is probably in baseball, where the actual dimensions of the field change, depending on where you're playing.
I hear what you're saying though. When you've got to overcome a large deficit, the support from your home crowd may be that extra boost you need.