There is certainly a risk of false positives and there is also a risk of disproportionate data retention, meaning that if there aren't safeguards against racial profiling on either side of the border with information that is then collected and shared between both countries, there is the concern that the databases of information skew disproportionately on the basis of those who have been profiled. That, again, contributes to the unequal treatment of individuals' privacy rights and data if some subset of travellers are more likely to have their information shared and retained. That is certainly a concern.
On October 24th, 2017. See this statement in context.