Save game is here
Dominion Declan Fleet XXI is the one to look at in this save.
When you add a commander to a fleet, you get a bump in logistic, 25%, IIRC.
But if you promote that commander to an admiral, you lost that logistic bonus. You get +25% weapons and defense in the fleet, but revert back to the previous logistic. You also lose the previous bonus of "double the fleet move".
Looking at another fleet, Dominion Norway Gladiator Fleet III, if I upgrade to a privateer, I lose my command ship and my logistic reverts to the base of 81, although the fleet will show 88/81 logistics. As long as you don't dismantle your fleet, it will stay intact, but you can't re-add ships up to the previous logistics (in my case 101).
Was that working as designed? It seems weird that granting a promotion kinda acts like it's a new type of commander, not an upgrade. Right now, there's not much incentive to promote a commander to anything, except maybe the navigator that becomes a powerful survey ship.
Maybe the commanders should gain in experience after each battle, like assigned citizens to a planet? And after Level X has been reached, a promotion is then available that further increases the bonus? Hmm, or maybe that will unbalance the game too much, especially at higher difficulties against a powerful AI? Any other thoughts from people here?