This reminds me of the first boss on the N64 game Lylat wars after you pass under the waterfall on Cornaria.
I think this definately suits Liberty more than the current Star Wars Carrier, however I am a bit concerned at the lack of details at the front and back of this model. I'd like to see an unrendered version if possible, to see where the curves and other minor details are, as I cant see them on the front or the back much...
Also, the Osiris should not be replaced. Maybe the hitbox altered in some way, such as making it like any other nonvanilla ship, but the model itself is a great one. Any vanilla models are used as a basis to design the rest of the respective faction's craft from, so I do not see any benefit in removing the vanilla models or changing them.