That’s dependent upon variables such as your choice of propellant, how you’re generating the electricity your thruster needs, on the type of thruster you’re using, and how efficient it is. Should you have a specific model in mind, Accion provides some numbers here, from weight and maximum thrust to impulse and power required. One comparison you may look at is the X3 thruster; it’s supposed to be more efficient than older Hall effect thrusters. I will update with a more specific comparison later, or someone else can modify this as appropriate.
Okay. So there aren't any easy comparisons, as thrusters generally aren't mass-produced, but let's take a shot at it. Tsiolkovsy's rocket equation [Δv = Isp * g0 * ln (m0/mf)] tells us how much change in velocity we get for a given exhaust velocity (or in this case, specific impulse times standard gravity) and amount of propellant. Applied to Accion's largest thruster, the TILE 200k, the dry mass is 16kg, the Isp is 1500s, and here's where we make our first assumption, that the wet mass of the spacecraft (dry mass plus propellant) is just the weight of the propellant, thruster, a panel capable of supplying 280W (roughly 0.6kg), and in the TILE 200k's case, the power processing unit, without accounting for any useful hardware (a bit silly, but this is a useful enough comparison). Let's say the wet mass is 20.6 kg. We plug these numbers into the rocket equation:
Δv = [1500s * 9.81 m/s^2 * ln (20.6 kg / 16.6 kg)], which gives us a total change in velocity of 3,176.8 m/s.
Now, let's take the X3 thruster. The numbers I get from the University of Michigan's page range from 1800s-2650s for its specific impulse, with a given dry mass of 230kg. It's been tested using 100kW currently, so we'll have to include solar panels (or a reactor, but we'll go with solar panels for now). The most modern numbers I currently have say 447W/kg, which means we need approximately 224kg worth of solar panels, giving a total dry mass of 454kg. We'll include 46kg of propellant to round it out to 500kg total. Plugging into the rocket equation, we get:
Δv = [2650s * 9.81 m/s^2 * ln (500kg / 454kg)], which gives us a total change in velocity of 2,508.95 m/s.
Almost 700m/s difference, while the system using the X3 has 25 times the wet mass and about 11 times the propellant required. Quite the difference. This comparison has its limitations, given that I didn't include any payload, and spacecraft design has all sorts of tradeoffs imposed upon it (lifetime expected, money available, what technology you have access to, environment it's supposed to operate in, and so on), but at first glance, Accion has an impressive little system. If you like, I can add more detail another time.