I'm pretty much of the opinion that, short of extraordinary situations of mental illness being managed properly with meds for oh, at least a decade, that releasing a serious sex offender always poses an unacceptable risk to society.
Simply put, there is NO therapy/drug/other mode of treatment that reduces the risk of recidivism to 0 or near-0.
Would some of the offenders in that group never again commit the same crime? Sure.
But given, say, a 100 person pool wherein 70 people will never again commit a crime, 10 people will commit a crime but will lie to be released from prison, and 20 people are obviously sick enough not to deserve release, what's my take on it? Lock all 100 of 'em up, because I'd rather have all 100 sex offenders pay for their crimes forever than to risk even a small percentage of them returning to their crimes.
This whole "giving people second chances" thing is taken too far, sometimes. If the victim of a serious crime has to live with that crime forever, the criminal who committed the act should, too, especially in light of the fact that there is no way to absolutely guarantee that he or she will not commit the crime again on another person.