Is there an advantage to using the AGI AC/DC Power Supplies over using deep cycle 12V batteries?

Yes, see below for a few advantages.

• Less Weight: 12V batteries are very heavy. A small motor generator and a little gasoline weighs less than one 12V deep cycle battery and will last you several days.
• No need to charge, just refill the fuel: Batteries need to be charged for several hours. Imagine arriving back at your hotel after a long day in the field (We all know surveys can last late into the evening)—you will only have a few hours to recharge the batteries before mobilizing the next morning. A few hours may not be enough time to fully charge your batteries.
• Less Bulk: Depending on soil conditions, you may need 4 or more 12V batteries to power the SuperSting™.
• More Reliable: Surveys can be interrupted if batteries change voltage rapidly when tipped over or moved when powering an instrument. Internal battery cells can be damaged during transport causing unreliable voltage draw down and intermittent spikes.
• Less worrying: Batteries can go bad at any given moment and need to be replaced frequently.