I own the SR-80, but haven't heard the K401. But from what I understand reading this forum, they sound very different. The Grado has a much more up-front sound, which probably makes it more suitable for rock. I love mine for rock, energetic jazz, and other music with some energy and intensity.
The Grado also has much lower impedance, which may make it easier to drive to listenable volumes without an amp. However, they're very open (not sure how open in comparison to the AKG), so they're not very good for portable use.