Another possibility would be to release a T5 Venture Class Retrofit.
The T5 version could have a BOFF layout like this:
Tac: Lt. Cmdr
Engineering: Cmdr. and Lt.
Science: Lt. and Ensign
Consoles: 3, 4, 3
Everything else: exactly like the Galaxy -R. (turn rate, Crew, etc.)
The advantage of this would be that Cryptic wouldn't have to make it a Mirror ship at all, they could release it just as T5 version of the Venture. Additonally, would L O V E <3 it if the availlable ship parts (Envoy, Celestial, Galaxy and Venture) would be availlabe for the T5 Venture Refit also.
Price: 2500 ZEN or 1000 ZEN if the player already owns the T4 Venture.
As a Bonus the T5 Venture comes with one [large Phaser Array MK XII [Acc]x2 [Dmg]]
This weapon (only forward) fires once per cycle at a 300 degrees arc.
[Console - Universal - Antimatter spread], [Console - Universal - Saucer Seperation] and [large Phaser Array MK XII [Acc]x2 [Dmg]] are the 3 part GCS set. This set is only equipable at the Exploration Cruiser retrofit or Mirror Exploration Cruiser.
2 part set Bonus
+5 power to all sub systems
+30 Starship Energy Weapon Damage
+30 Starship Projectile Weapon Damage
3 part Set Bonus
Clickable power, 3 min cooldown.
It fires a combined high yield Photon torpedo spread at 3 targets and fires a phaser lotus like attack with the large beam array. This 3 part set bonus is deactivated once the ship is in seperation mode.
As you can see the Special item and the Set bonuses are the same as the Multi Mission Galaxy Cruiser has, as posted above.
To get the whole Set, the player had to buy the Galaxy -R too. So Cryptic could make money with a ship they have released for a long time.