It's quite accurate, and I can find things ahead of time that I would otherwise never know until the room was built and the system installed. And many churches don't have programs that need these systems. They can be much more expensive as well. As for complexity, this also differs from project to project. A local salesman is telling me cross matrixing is right for my church.
Digital processing is also a requirement for a cross matrixed system.
TEF is best for just room measurements, Smaart is fast for system setting. It is faster than TEF in some ways. But using both is a really neat trick. TEF helps you to find acoustical problems like reflections and echoes. When I design a system, I pick a speaker that fits the room.