One issue I have not seen addressed is that you now have to make sure the same person uses a pass after the first entry. In the past there was no need to keep Dad's seperate from Mom's, and DS seperate from DD, etc, etc, etc.
Now, with the first use, the biometrics are in the system for the person who used that pass. If for some reason mom gets the pass that dad used on the initial entry, it will be rejected on future attempts. In some cases it may be easier for a CM to attribute a failuer to demagnitizing rather explain the system has changed and your old habits may no longer work...JMHO