I don't think the flak turrets are absolutely necessary. maybe a nice addition, but I'd not have it too drastic, maybe half of what tec hangars get.
aside from that:
1) small fleet of carriers is relative. I mean, if your starbase is maxed out on hangars, then you have 14 squads (or 20 for advent). you'd probably want to staff them with fighters, because defensively they are just better at killing whatever threats the starbase cannot kill itself. so, let's say you have 14 fighters. well, you are aware that it takes quite a bit of force to overcome this, are you? I mean you'd need probably a good 10 fighters squads to occupy the defensive squads and then a bunch of bombers that attack the base itself, say another 10 squads. that's 20 squads or 10 carriers. not such a small fleet after all I'd say.
Yes I agree, allthough I have been attacked by fleets consisting of 2 to 3 times that many. It was a good thing I had a few hanger bays and deffence turrets in the vasinity. Gave me the time needed to get a fleet there, I don't think it would have survived if I had'nt. Probably still would have been able to bring my SB down, if they hadn't retreated. I wouldn't have lost the GW though, and thier fleet would have been creamed. This to me is what makes a game intersting.
2) you have to study your enemy and adapt to him. if he spams carriers then forget about the weapons upgrades and go for hangars. if you are in a neutral well, adapt to the circumstances. that's why we have the option in the first place to have something different and make you think what you do different in that situation. uncolonisable well means no hangar support? fine, then if you're worried about carriers, make sure you get hangar upgrades.
I agree, in fact I would argue that it would be good if you were able to scuttle upgrades and not the whole SB. just for that bit extra adaptability.
and at long last, don't isolate your view of the thing. the harder it gets to destroy a sb solo, the even harder it will be to destroy one supported by fleet.
This statment makes alot of sense to me. Late game when fleet research is maxed and fleet capacity is maxed, and in good close games fleets are of a similar strength (or even if you have the upper hand with your capitals expience), having Sb's even stronger in deffence will just lead to most games ending in stailmate.