We need a medic!

How about the addition of a Medical Ship to Sins? It would be a ship dedicated to helping planets that have just been bombarded to quickly reestablish it population or can also be used to keep a planet's population numbers up while it is being bombed. You could either have it land on the planet itself or defensively move to keep away from the attacking ships. Keeping your planet's population up would, or course, come at the cost of crystals, metal and money. You could also have features as Super Shields, Thick Hull, Antimissile Defense, etc. to make the more battle-hardened ships more useful in the field. This could be a feature that allows you to add a further defense to a planet (other than planetary shields) that would keep you from losing it altogether. BTW I would not see this as a feature that would directly help an attacking fleet but would otherwise be used to help keep the planet you have rather than make your armada more powerful.