I bet the Sierras have good extension, but nothing beats a quality sub. It adds more depth. You might have to experience Hellboy again. It's night and day.
OK, I'm a believer now! Watched The Dark Night and it was quite an experience. My son and I were frequently looking over at each other and just giggling at the LFE. The sub is great with music, but movies are night and day, just like you said.