Perhaps there are a few more things you could maybe hash out.
Like the difference between being shot with a 12 ga load of buckshot or a 9mm from a handgun.
Like the different reactions you'll get from an average punk who sees: A. (What he thinks is) a sawed-off shotgun come up at him v. a pistol, or B. His cohort get shot by (what he thinks is) a sawed-off shotgun v. a pistol.
Like how you don't move unless you're going to better cover, or if you're part of a team doing the shoot scoot & shout routine to press an objective. If you never go anywhere without trained armed friends you can trust not to get too stupid under fire, then MAYBE such movement would be ok, although many including the authorities and pretty much every rational civilian firearms instructor would say otherwise. We're talking about defending against a criminal or a whack job on the American street, not closing with and contacting enemy combatants in some other country.
Like how if you do move to better cover, you haul a**, you don't "groucho" or whatever the current fad is so you can shoot accurately. If you can run flat out as fast as you can and still shoot accurately, by all means carry on.
Obviously the greater power factor is the primary advantage of the shockwave over a handgun. No dispute there. However, that greater power is of no benefit if it can't be brought to bear or you lose control of the weapon.
In what type of scenario would you be using the shockwave for "defending against a criminal or a whack job on the American street"?
I have to expect any personal defense encounter I'm involved in away from my home will be reactive. Obviously the shockwave is not a practical concealed carry weapon so all those scenarios are excluded. That leaves defense scenarios in or around your vehicle. I don't think too many people would make the case that the shockwave would be more effective or practical than a handgun to use from inside the car so that's out as well and only leaves grabbing it and exiting the vehicle.
The handgun can be kept more readily accessible, is quicker to bring into action, offers better retention and can be operated effectively while in movement. The degree of movement necessary varies and I never referenced any particular type, but movement is nonetheless often a key component is such instances since at least one party will try to maneuver around the vehicle to get a better shot. There are plenty of videos to verify what typically occurs. And it's not all about gunfights. Scenarios involving unarmed assailants or those armed with contact weapons occurring at extreme close-quarters must be considered. With a handgun, I have a free hand to utilize in ECQ encounters and better retention compared with a two handed weapon. Creating separation is often the best response and is much easier to do with a handgun.
And yes, I have spent a lot of time training to be able to put rounds on target while GOTX or more accurately, while exploding off the X although that degree of movement isn't always what's necessary.
In terms of home defense and having to move through a home or otherwise being forced to maneuver in confined spaces and negotiate corners, a pistol grip shotgun still requires two hands to operate and lacks the weapon retention capabilities of a handgun. The handgun also retains it's functionality even if the free hand is busy doing something else(opening/closing doors or windows, operating lights, ECQ defense, calling 911, carrying a child etc.). Not so with the shockwave.