Yeah, I've seen that before. I think once you get past the problem controlling two ships (mind you, not a small obstacle), the game would actually be easier that way.
You see evidence of it against the first boss. He uses the black ship to block the black shots while the white ship behind lays waste to the boss.
I like Ikaruga, but I'm no where near hardcore enough to try to perfect myself for the game. It's fun to play every once in awhile, but not fun enough for me to practice at it.