Looking at the costs in M+C and E, right now the controllers still favor choke points, not true distributed defense.
The M+C costs are just build-time. The energy cost would be a real preventer of distributing them everywhere, and in that they match the base Mk I turrets. So while I hope that resource costs come down to build the turrets (16K to 70K per turret is very expensive, up to 4 million for a planet 4-cap), the more important thing to balance is the ongoing energy cost.
At 200 to 800 energy per turret, and up to 24 turrets per controller per planet, energy can add up FAST. 50,000 energy (1 matter converter, or -100/-100 m/c) will supply 250-ish turrets best case. That's about 10 turret/planet caps, or 2.5 planets of a full 4-cap deployment. If you have 10 planets, that's 40 caps, or at least 200,000 energy, or 4 matter converters (-400/-400 m/c), or 1 system energy collector + 1 matter converter (-100/-100 m/c + 20 AIP). Worst case (Lightning, Flak, Sniper, Spider) is 46,000 energy
per planet.
So, yes, distributing them everywhere has a cost. I disagree that it still encourages chokepointing, however. A 4-cap set of Core Turrets can do almost 2,000,000 DPS without multiplers. That's basically a Mk II Fortress. Putting that kind of defense only on your chokepoint, where you probably already have several times that much firepower, seems a waste to me. I think this is the sort of thing you spread to anywhere that might be attacked, and more. Especially on your planets with Uniques, where chokepointing would be both risky and wasteful.
Free, for that kind of ability, is just too much. I will agree, though, that the costs need some fine-tuning, because the per-planet caps of Core Turrets mess up the calculations that were used to get the resource and energy costs for base turrets.
That said, is there a reason that 4 and only 4 and exactly 4 core turrets controllers are available per map? Why not all 8, or a random selection between 1-8, etc.
And what do other people think of the idea of making controllers either give a general cap (+X turrets of any type) or a all-turret cap (+Y turrets of each type)?
Right now, like Fabs, there's major variety in what controllers are available. But if you roll Flak, Lightning, and Spider on one map... well, there may be disappointment.