EDIT: This is at NORMAL ship caps, not high caps as shown in Keith's original post. Double these caps to compare against the original post.Took a swing at turret combat stats and came up with the following:
BasicWent much beefier on this turret, and the armor is key. You get about 25% damage reduction against the average triangle ship, which makes the Basic unusually hardy. At the same time, anti-armor units will be more dangerous to the basic turret. The reload reduction reflects the fact that 8 seconds is just too long for a front-line turret to expect to live to get a second shot off. With a lower reload it now delivers more damage while it lives. Armor boosting should help this turret nicely.
LaserThis picked up the longer reload time from the Basic, giving it a much heavier attack. It also got a touch more Armor Piercing. It is reasonable durable and has some armor to fend off lighter attacks.
MLRSThis turret got a decent boost to its damage and it actually has among the highest Cap Bonus DPS values relative to the triangle ships.
MissileThis took a slight hit. A touch lower damage and a smaller cap. The increases in other turrets should easily make up for these changes. It also has higher health so it should survive against longer-ranged enemies much better. So a trade of DPS for consistency against various bonus ships.
FlakHuge health increase here, and I considered going higher. The damage came down, but so did the reload by a second. I really want these turrets to mount a single Shield Module that auto-builds and you can't control. Then 80% of their health could be put in the Shield Module, and 20% on the turret itself. This way their health could be pushed up even more but they'd be vulnerable to ships that ignore Force Fields. Auto-building a single module that you have no control over might hopefulyl be acceptable for the base game. But I set the stats above without that in mind. I should note that I used roughly 2/3rds the actual AOE targets for calculating DPS, which is why this lists 4 instead of the actual 6 targets it can hit.
LightningArmored like the Basic, but with 250% the health, this turret should be able to survive much longer. I tweaked down the reload from 18 to 15 seconds, which should increase the reliability of a second shot. The damage came down, but since it ignores armor, that's completely countered by the reduced reload time. Again, I've used 2/3rds the expected targets which is why it is 5 shots AOE 25 instead of 5 shots AOE 40.
SniperWent with a much lower cap here, and the damage went up. Then I bumped up the reload from 6 to 8, which seems more respectable for a sniper, which caused the damage to go up even more. This turret now murders lone Raid Starships. You just have less of them to spread around, so you can't just carpet every system with 15-20. It might even be possible to let the AI have human Raids.
SpiderThese got completely reworked from "Sniper+" turrets to something closer to the bonus ship. They've lost their sniper range, but gained 3 shots and a lower reload, letting them really play to their engine damage role. Their bonuses were changed to x3 versions of the Spider bonus ship.
HBCJust a slight tweak to its damage and a big buff to its health.
Gravity/TractorJust cap tweaks to put them on multiples of 8.
PS: Completely against mobile turrets. It is silly and will be annoying. Fortresses moving is already a bit annoying when they accidentally move for some reason, or when I select them along with other random things. We already get mobile defenses with turret unlocks. They are called drones. If they aren't good enough, fix that. Leave turrets stationary.