John Gruber (of Daring Fireball fame) has been using SuperDuper since at least 2004, not long after its initial release. He’s written kindly about it over the years, and has just issued his verdict on SuperDuper 4:
SuperDuper feels like impossibly good software. Read his post announcing version 4 to start, then catch up on the rest of the blog to get a feeling for how much work he’s put into SuperDuper 4. Just extraordinary.
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I recommend SuperDuper 4 wholeheartedly.
Thanks, John!