I own one of their DPVs, Pete, and it's uniqueness stems from (1) light weight out of the water, and (2) five variable speeds.
The lightness out of the water makes them easy to carry and handle, without the need for a dolly to transport and move them. With the standard nose cone and a NiMH battery inside, it weighs about the same as a 40 cu ft stage bottle and regulator. So you can thus easily clip the DPV to your right shoulder D-ring and walk into the ocean with it across the beach. For boat diving, it is easy to hand down to the water or back up to the boat upon entering and exiting.
The variable speeds allow you to synchronize your speed with another diver, or else to fly quickly underwater, or else to preserve your battery usage to its maximum 60 minute run time.
The most common battery choice is the NiMH which gives up to 60 mins of run time, however they also offer LIon (Lithium Ion) which offers 120 mins, when operated conservatively. However the airlines will not let you transport the LIons.
You can also order their extended nose cone, which holds 2 batteries, and thus extends your run time to 120 mins or 240 mins respectively, with NiMH or LIon.
I did not mean to speak for AG, however these are easy questions of yours, so I thought I would reply. Hope that's ok.
The X-Scooters perform flawlessly, and so I highly recommend one for you. The only reason to consider a different brand would be because some groups mandate lead-acid batteries rather than NiMH or LIon, which is a bit old fashioned, in my opinion, and therefore they might shun you if you showed up with an X-Scooter, which is currently the cutting edge, ironically.
The dynamics of scuba diving with a light weight DPV is revolutionary. The power of the vehicle is not only an added thrill, and not even also alone an added tool, but also an added measure of safety since it gives you many more options to deal with a strong current, or to return to the boat or the beach. But of course the added safety consideration is not to get so far away from your platform (whether beach or boat) that you cannot return on your own. The buddy system with 2 DPVs between the buddies resolves the distance issue. There are towing protocols and procedures for a failed DPV.