I've heard of the three-Nacelled Sovereign before. It's apparently called the Macbeth class. I think there was a model of it on Battleclinic for Starfleet Command 2.
As the shiplist currently stands, we've got over four HUNDRED models. 99% of which have been made, acquired, modified, or retextured by Kenneth_of_Borg. Dafedz has also painstakingly worked out all of the ship stats. All of this work took hundreds of hours, and I seriously doubt either of them would relish the idea of spending hundreds more hours working on an expanded shiplist when we've already crammed so many ships into the game.
There are also other issues with doing this. We want the game to be as canon as possible. The Galaxy-X was part of an imperfect alternate timeline that was created by Q. And recent events in Trek mean that this timeline could never happen. (The Enterprise-D was destroyed and Picard found out his future and changed it for instance) The idea that the Federation would develop and implement a superweapon that could smash through both the shields and armor of a Klingon Battleship in a single shot is also rediculous - the Klingons would have gone to war with the Federation if they did that. So technically the Galaxy-X isn't a canon design, even though it did appear in the shows.
As for the Yeager, yes, we could put it in...but what about all of the other canon ship designs that are "missing"? There are the Cheyenne, the Curry, the Nebula variants, the Niagara, Peregrine, Springfield, and Sydney classes to name but a few. These ships aren't in the shiplist for the same reasons that the Yeager isn't in; the Federation has more designs than the other Empires already, and it was hard enough to balance the existing classes against those of the other Empires. Adding more would simply make it even harder to balance out the ship designs.
On top of this, you've also got to thing about filesizes. Adding more models means bigger downloads. I believe that most of the models are around the 500kb-2mb mark each. You could be looking at adding another 20mb to the download just by adding the few ship models that I mentioned above, and this doens't take into account the database entries and 2D images needed to make them work ingame, which could potentially add another 500kb download per ship. Plus you have to factor extras in such as the ship voices and special effects. All of this extra data might not sound like much if you've got a broadband conenction, but there are still people out there on slower connections. And someone has to pay for all of the bandwidth the game will need as well.
Now obviously you've mentioned most of these problems in less detail already, so i'm not trying to nag or shoot down the idea. I have to grapple with many of the same issues when adding in new buildings or images to the game myself. But adding more ships could potentially be more of a problem than you might realise which is why i've mentioned all of this. Ships can also easily be modded into the game at a later date, so even if they don't make it into the official release, they can always make it into the game later. I'll probably end up modding in the Cheyenne, myself.
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