Thoughts on Hearteater's changes:
I don't like the cap-reduction of Sniper turrets, since Snipers are my go-to turret for non-fortress world defenses. I want to be able to have highly variable amounts of them present on any given world based on my perception of what is and isn't worth defending and what is and isn't at risk. Increasing the power density of the turret reduces my ability to vary the level of defense I put on any given world, even if it makes the turret 'better' over-all.
I really don't like the change to Spider turrets. These are the only upgrade you can get to sniper turrets, so why is it a problem that they are the "Sniper Turret+". My use for spiders is to slow things that are on the planet, not kill them, and if I want short-range slowing potential I already have gravity turrets and tractor beams. Snipers and Spiders are long-range stall weapons, Gravity and Tractor turrets are short-range stall weapons, and most of the rest are short-range kill weapons. Why do Spiders need to move into the short-range stall/kill group?
Tractor Turrets - changes here don't really matter to me as long as the total number of tractor beams remains the same, although keeping higher mark tractor turrets longer ranged helps for grabbing parts of passing groups of ships without taking fire from the full group.
Gravity Turrets - if the range of the higher-mark gravity turrets are reduced to the value in Hearteater's table, those become less useful. Don't really know that that's a particularly bad thing, though.
For the rest, I don't really care either way. I don't really like reducing the total available number of turrets from a firepower granularity perspective, because I can more easily fine-tune defenses if I have 100 turrets to play with than if I have 75, but the firepower bonus is nice.
Honestly, though, I think the only real problem with current turrets is that the knowledge cost is a little too high. Bringing the Laser/MLRS/Lightning/Flak turrets down to something like 1000/2000 for Marks II and III and bringing Missile II/III down to 1500/2500 or 2000/3000 (because its range is so much greater than that of any of the other turrets) would in my opinion make combat turrets with their current stats reasonably worthwhile. Flak and Lightning turrets could perhaps be made even cheaper, or they could be made more durable, since they are low in number and have to be closest to their targets. As for utility turrets like tractor beams, gravity, and counter-(weapon), I'm only going to unlock those if I need extra tractor/gravity coverage beyond what my current turret caps give me, and counter-(weapon) turrets if there's something threatening enough that I feel a need for them.