Do any of the 3V devices utilize both automatic and enhanced automatic powerdown?
Not really, but the enhanced powerdown devices can be connected such that they operate in both modes. The enhanced devices have an INVALID# (active low) output which indicates when invalid receiver levels have persisted for 30usec. Connecting INVALID# to FORCEOFF#, with FORCEON at GND, causes the device to power down after 30usec of invalid receiver levels, or after 30sec of inactivity on receiver and transmitter inputs.