About making a different model for the Lilith... I suppose that's understandable, as the Lilith is about 4x tougher than the joke... Cain, yes. However, the model is rather similar to the Fenris/Leviathan in the sense that it's a much tougher frame built upon a similar planform.
This said, the textures should be brought to bear next. All FSU VP models I've seen to date most certainly enhance the detail of the model, but also remain quite true to the designs presented on the original texture (or, at least in spirit). I've never seen any exception to this released in the FS2 MediaVPs.
I like the details (especially what you've done with the "arms"), but the original model/texture/additional appearances in game, etc., factor(s) must not be omitted from consideration. The Cain (or Lilith) is just not the same when it's too different.
-Thaeris