It just seems that a big ship like the Akira is more suited for the Cap Ship Slot than the Cruiser Slot.
Really, having the Defiant as a mean little Cruiser Killer compliments the Capital Ships very well. I remember a discussion about different types of weapons and damage, where the classification of a weapon's type effected damage to a particular kind of ship.
The biggest thing I see here is people are afraid to gimp the Defiant, or make it a god ship.
If you place it in the Cruiser pool at the top with plenty of cost and upkeep, equip it with anti-cruiser weapons, and a nasty set of teeth, it still turns into the "tough little ship" we all know and love it for. Its a good counter to the bulk of an enemy force as cruisers make up large portions of any developed fleet, and the upkeep could be so that it can't easily be spammed and abused, but low enough that you get what you pay for.
And once you do that, you leave the Akira to fill the Carrier Cap role where it can really shine.
To me, its a win, win.
Problem is its a lose lose situation, and i'm gonna tell you why. Both of these ships were created to combat the borg. Each of them are OP by their own standard. you have a ship that could literally destroy of disable a small fleet of its own and you have a small ship with enough firepower and defenses so lets break it down.
Defiant:
4 x pulse fire disruptors (pulse phasers in some places)
1 x Aft phaser array.
2 x Fwd quantum torpedo launcher
1 x Aft photon launcher
damage output 60,000 terawatts
now lets do the math.
5 weapons = 12000 terawatts each
4 pulse are doing 48000 terawatts per shot, usually fires in rapid succession of 3-5 shots
Akira:
5 x Phaser Arrays (270 degree coverage)*
15 x Photon Torpedo Tubes (Pulse Fire Tubes)*1
damage output 22,500 terawatts
now lets do the math.
1 x Large Saucer Array (Dorsal) 11,250 Terawatts
2 x Medium Saucer Arrays (Ventral) 2812.5 Terawatts
2 x Small Lateral Arrays 1406.25 Terawatts
Now in theory how emitter arrays are explained, the more emitters on the array, the more powerful the phaser is suppose to be.
(*) Currently it is disputed that the akira actually has 7 phaser arrays. the offical canon spec states 5, the model contains 7, the other 2 small arrays are located on the aft end of each nacelle
(*1) pulse fire tubes fire at a rate of 4 torpedoes/sec with a 1 sec reload. 350 torpedo compliment. 5 volleys total.
Notice that i did not mention what the power output of the quantums and the photons are suppose to be becuase no where in any canon spec do they reveal what the actual yield is per torp! there is no canon spec.
if there is any ship which is really underpowered it is the vorcha. the vorcha's output is 60,000 terawatts she is suppose to be on par with the galaxy. the galazy has 11 phasers compared to the vorcha's 12.