Hmm, about the SOTA missile beeing better then the 300 year old refined. I suppose this could also be a speciality of a given empire. Some empires might do great technological breakthroughs, while others achieve a similar rsult due to small refinment steps.
But of course, if the old empire ever learns how to build those nifty new missiles (having lotsa problems to even understand the concept), it should be able to adapt its 300 year experience fairly easily to the new missile type.
And vice versa a more pushy empire might be able to make quick breakthroughs, but applying those valuable (and cost effective) refinments should be hard for them.
So while the dmg/money looks like a stair for the "active2 empire, it would look like a straight growing line for the other empire. The average increase would be similar though.
Past public reviews and discussions.