So according to http://memory-alpha.wikia.com/wiki/USS_E...CC-1701-J) the Enterprise J is about 2 miles long.
And will still have the same amount of Consoles and Bridge Officers = Firepower as an T6 Escort. Makes perfectly sense.
But I do have to say... I really like the Romulan Ship. Looks like the embodiment of the Romulan Republic Emblem.
Edit: Obligatory Drop Chance addition:
Lockbox ship = ~.45% chance = 125 Zen for a key (95.6 Zen when buying a 20 Keyring on Sale)
Promotion ship = ~1.1% chance = 300 Zen promo pack (250 when buying the 4pack)
The odds are (somewhat) normalized with the cost.