It almost looks like the number of arrays are irrelevant in the case of this new ship, as we saw multiple simultaneous beams emitting from the same strip along the length of the primary hull. Can't remember if either the E-D or E-E could do that. The advantage comes from the actual power the ship can generate and send out through the strip. Arguably, the Galaxy and Sovereign classes, having larger warp cores, should be able to put out a lot more energy than smaller ships, but then we've seen how "overpowered" smaller ships like the Defiant could bring the larger Lakota to its knees in combat. The experimental nature of this ship (curiously, why doesn't it have an "NX" designation if it's supposed to be experimental?), it having two warp cores and the extra unidentifiable "thing" in the engineering section, could conceivably be one of the most powerful ships in the fleet - certainly the fastest. Kind of weird they would have sent it out to hide on some distant rock somewhere. Definitely a lot of mysteries being set up with the Protostar alone.
Every Phaser Array Element has a maximum energy output limit, ergo the need for multiple elements.
This not only provides wider firing arcs, but provides many emitters to fire out of simultaneously.
And with advanced Energy Capacitors / Batteries, who knows how much energy you could have stored before battle to power each individual element within the array.
The Defiant seemed to consume their
Power Cells relatively fast. But given how powerful the bolts they were firing, I'm not surprised that they wore out the Power Cells so easily and it needed to be replaced.
The
Series 5 long-range tactical armor unit had a "Condensed Energy Matrix" which which alone could power a fleet of StarShips.
Imagine a hybrid Capacitor/Battery that gave out enough energy to make a small meter long torpedo go to warp, have shields, sensors, tractor beams, and energy weapons.
That's insane how much energy you could cram into that unit.
And I'm sure Voyager scanned the Druoda "War Head" and knows the structural makeup of every part of that projectile.
The most valuable part IMO being the incredible small portable power source that is the "Condensed Energy Matrix".
That much power, that fits in the size of a meter long tube that can be carried by two crew members is game changing.