Enlighten me o wise one
Really? A reserve tank is as great as endless air supply? The Power Tank's were great until the invention of the Lithium battery that can be recharged off a USB port. Way back in the day you could run some air tools off the power tank if needed, as well as inflate your tires. Somewhere along the way someone made a kit to run your lockers. These days companies make battery powered tools with more power/torque than you'll ever see from a 10lb tank of CO2.
Not to mention the Power Tank is large. It's a bulky kit to carry and mounting options are awkward. It also cost you ~$15 to refill after you've pumped up your tires about 4 times - that's more expensive than the gas station air pump.
The Power Tank is fast at airing up your tires. Probably takes about 45 seconds to 1 minute per tire, which is pretty good. The ARB pumps take about 2.5 minutes if you don't have a reserve tank. If you got all crazy and made a bracket to fit the Rover, a York pump would take about 20 seconds per tire and you could run an impact at the same time.
The 12v pumps are a smaller package, easier to tuck away, and never run out of air.
Power Tanks fill your tires faster. I can't think of another good thing to say about Power Tanks.