Does the Antenna Genius 8x2 Plus disconnect the antennas to the Flexradio, when power is removed?

If you mean the Flex power the answer is yes.  If you mean the AG power the answer is still yes.Actually the antennas are disconnected when SSDR or Maestro is shut down and the radio is left powered on as it is in my configuration at my Remote.

I can tell you Kevin that the AG 8X2 + also switches very well using the BCD  connections to the Flex 6K  usb ports.  That method does not allow for switching to 60M at this time.  Also , if you do not require SO2R inter connectivity,  the 6X1 or 8X1 Genius is a less expensive choice.  Personally I prefer the flexibility of the 8X2+. when used with a Flex radio with 2 ADC's and the PG XL amplifier.

Are not the antennas grounded and the port A and B as well when power is disconnected to AG? From a lighting perspective still risky as we are talking about relay gaps and the possibility of transient spikes reaching ANT1 or ANT2 of Flexradio.

Hi Kevin,    The software disconnect of Antennas in the AG occurs when using the LAN connection option of the AG to pick up the Flex6600 Band information.  If using the BCD or other hardwired feature of the AG 8X2 you would need to shut the Flex radio off to actually disconnect the antenna connection.     Remember also that you are protected only by the relay gap in the Antenna Genius itself.  The AG is still vulnerable to lightning damage as the antennas are still connected to that unless you use some sort of external antenna grounding scheme such as poly phaser to lessen the probability of equipment damage.  Nothing is going to stop a direct antenna hit however.  The best you can do is keep the equipment and antenna grounding as equal in ground potential as possible.