As you are aware, the Bullets are no longer supported.  They were notorious for failing.  I never purchased one but they got pretty beat up on their own forum. 

Ubiquiti has used Passive POE for a long time and the majority of their devices run on 24 volts.  I've got a big box of unused power supplies.  Anymore, if I'm going to be installing more than one device I use a Toughswitch, Edgeswitch, or Unifi Switch.  The Edge and Unifi switches can handle both Passive and the 802.?? POE standards.  Also, its my understanding that Ubiquiti is moving away from the Passive standards.  Last fall they indicated they were going to quit manufacturing switches that output 24v but after some "encouragement" by users on their boards they announced that they will continue to manufacture current models.  No guarantees on 24v for new switch models.

My biggest learning experiences with the POE adapters has come from shoddy (on my part) cable installations that have allowed water to enter cable jacket and work its way down to the POE adapter.  Once it gets there it shorts out the adapter and resets the radio.  Fortunately it's only a reset and not fried!