Trying putting 5 engineers and 1 repairman (high level with 120+ vets) on your Moltke. You will be zipping around at 57 knots with 3 minute overheat. With that much speed you can chase after planes. Oh, the 900 soft Def plus the 110 repair/second should allow you to take a full broadside from a BB2 and survive. So stick your neck out a bit by moving yourself in front of the BB line to shoot up scouts. If you get hit, run back and repair and then do it again.

Imagine if you raise and lower the height of your planes.

oh you KM AA spammer lulz...
You need to aim first, then shoot <- the best ammo saving mode ever!
But since you are smart at aiming, you would figure out, that the longer range you have, the more efficient time for aiming is spent.
And yes, KM has long range AA capable guns with GA of 29 - that's what i'm using.
Or even with 28 GA, but reload is bad for those and huge gun space requirement, and main gunners requirement... - which makes them immpractical.

But still, the best AA ingame is on IJN, the variety ranging from 25GA to 48, variety of reload aa shell damage, and muzzle speed.
And exactly this variety makes IJN AA the best.

AA capabilities comparison (in brackets - major drawbacks):
IJN > KM > MN(low AA shell damage) > SN(slow muzzle speed) > RN(limited ship T slots) > US(low range).
I haven't tryed RM AA though...  

And as for Moltke, it's a decent AA barge a.k.a. worth getting. 

KM has the best AA.
KM40 is the most reliable AA gun.