The speed with which it remakes fighters when they die, and the durability of the starbase means structure ships dont fly up and destroy it 5 seconds later, and yes while the hanger bays do provide extra flak coverage....I would rather have flak ships to provide that service since they are mobile I can move them to where the fighters are attacking (since we all know they are not always attacking in the area you want them to).
So do you mean to say that the starbase actually rebuilds squads faster? Keep in mind that the hangars are being repaired by both repair bays and the docking booms ability so they won't go down too fast, even to structure busters. If the enemy is there with his fleet, he can probably make mincemeat of your flak ships, but it'll take him longer to wear down the hangars.
You also cannot build extra hanger bays if the starbase is being used as a trade port gap filler in an uncolonizable gravity well, so it gets fighters (mainly to kill off merchant trade ships for extra cash =P)
True, the whole premise of my turtleshell idea is based on building at a colonizable world.
As for the docking bays...they are nice but 3 or more repair bays will repair more things at once than the starbase can and for approx the same cost (research+upgrade cost)...and they can be upgraded to repair more hull per second.
Keep in mind that docking booms repairs ALL friendly targets in a large radius, while also restoring antimatter. I was assuming use of both the SB and repair bays in conjuction, the repair bays doing the brunt of repair work, while the SB refills their antimatter and also adds a little to the repair effort.
My way is of course not the only way....but remember find the way that works best for you. Some times the trade port gap filler starbase will get a repair upgrade if my fleet is often flying through that area while fighting on different fronts. All depends upon the minor changes of the map/strategy.
Of course the turtleshell would have a specific situation in which it would be useful, such as a major chokepoint planet.
Ummm, I just realized something. My whole premise for this strategy assumes that docking booms targets structures as well as ships. The in game description does not give target information and I can't easily test my theory. Does someone have a definite answer?