There have been various threads about shifting above the factory redline. The consensus seems to be that it "should not damage your engine," but you have to understand that it is putting more wear on it than normal. If you want to search for the thread, it has some of the theory behind this. Basically, it has to do with how fast the components in the engine are traveling and how safe it is to move them at that speed.
If I were drag racing, I might consider it; it could probably shave some time off of your times. But for street I probably won't do it.