I don't really know much Dio era Sabbath, because I was of the mindset for so long that Ozzy era Sabbath was the only real Sabbath. I'm ready, now that I'm older, to expand my horizons a bit. Besides, Dio is a hell of a singer. A much better singer than Ozzy. Probably not as good a front man, but that may have to do with him being a tiny elf of a guy. Saw him live, and he blew me away. The guy still has a huge voice.