Secondly, you seem to be forgetting the massive benefit of using a Logistical or Military Orbital in place of an Econ Station, where upgraded Harvesters pose have no negative drawback in that regard. Not sure why everybody keeps ignoring that.
+25% damage for the whole planet, basically immunity to raid starships, powerful defensive translocation ability, and immunity to blades (this is huge against many melee ships) OR half enemy speed, double your own speed (which has already been doubled, so it's like quadrupled right?). And this is all just at level 1. Let's please stop pretending like that isn't a factor when taking into account the benefits and drawbacks of Harvesters vs. Econ Stations.
Just a clarification to this. Mil station is +19% bonus to all allies, not 25%. All command stations (including econ) double friendly move speed, but the logistics adds to the friendly move speed by a set amount. It significantly helps very slow ships (think siege SS) but it's not much of an effect on higher speed units (fighters/raptors).
My personal observation of the stations however was prior to the harvester upgrade, which used to be so dismal to not be worth upgrading EVER, I would immediately open MK II econs for the first planet I took and the first 6 would always get MK III other than the whipping boy(s), which usually got a Mil I for turret boosting. Mil stations previously with the translocation firepower was too weak to defend a satellite anyway so I simply econ'd the satellite systems as well, fully expecting them to self destruct (high-impact satellites would get a transport/cloaker/3 engis/colonization ship stuffed into a nearby system for rebuilds), except for the Fact IV systems.
When harvesters were less effective, I simply ignored the other command stations until very late game when I'd usually upgrade to MIL IIIs to try to help defend the outer colonies since their econ output was higher than the Econ IIs they were replacing. (Mil III is 96/96 where an Econ II is 80/80 + negligible Energy)
So, yes, 6 systems of Econ III not using logistics or mil stations, but otherwise, they really didn't change it that much unless your empire was HUGE. Those worlds in most of
my games tended to be hidden behind chokepoints, because of how I selected my maps, so that makes a huge difference as to their vulnerability.
So I partially agree with Wingflier here, there is an impact to not having the other stations on hand when you need to use the econ stations, but I don't feel it's an all or nothing scenario. It's reasonable to tuck your Econ IIIs in the 'back' and use the other upgraded facilities which are roughly equivalent to the Econ IIs. By the time you're at an empire of that size though I don't feel that it matters much however, harvester or econ. You're either floating in M+C and just building off mercenaries to keep it from hitting 1M/1M or you're fighting for your life with every inch of your econ. Late game seriously sees feast/famine econs, primarily because the bank is so small compared to the size of the fleet I'm trying to rebuild, and I fully support expanding the size of that bank, even if it's just the opportunity to build my own distribution nodes as emergency funds.
The econ is most fluid, in my games, in the early/midgame, where there's not a lot of systems taken yet ( up to about 5 or 6) so the econ strength is highly important to my ability to refleet to drive through a MK IV world eventually or if they're just brick walls. This is the time where I see my per second income mattering for the rebuilding of fleet ships while my fleet comes home for R&R, or if it was able to bank enough for a full rebuild.
In the games were I use Econ Stations, the border worlds simply don't matter as to their resource counts, I'd just take 'em and toss up Econ IIIs. In games where I've been concentrating on Harvesters, I usually only take worlds that have high collector amounts, which definately changes my galactic strategies.
I've just sat back down with my 9.6 game. At 5:45 and AIP 91, I've got 191k Metal, 570k Crystal, and 45,000 available power. I've taken 3 worlds, a 3/3, a 1/4, and a 4/3, all of them simply borderworlds while I scout. My homeworld is currently running two matter converters to keep my fleet and defenses powered and the fleet is prepping to head back out into the wild again.
My fleet, on a wipe, will cost me 4 Spire Corvettes ( 135k mats at MK I, 270k mats at MK II, so 910k in resources alone, not including modules), 96 Bomber Is (1600 each, 153k), 96 Fighter Is( 400 each, 38k), 96 Frig Is (1200 each, 115k), 4 Flagships (100k ea), 2 Neinzul Is (40k each). That's ~1.7 mill in mats to rebuild just the fleet, and mostly MK I, and most of it is concentrated in my bonus ships.
On a wave on average I lose the 'front line' of the defenses. That's 4 leech starships ( 100k ea), 2 FF IIs (48k ea, 96k/2), 3 FF Is (24k ea, 72k/2), 49 Flak I turrets ( 4.8k ea, 240k/2), 49 Lightning Is (4k ea, 200k/2), 5 Tachy Is (3k ea, 15k/2), 25 Tractor Is (7.2k ea, 180k/2), about 10 of my grav Is (7.5k ea, 75k/2), 78 Basic Is ( 2k ea, 156k/2), 38 Basic IIs (4k ea, 152k/2), 78 Laser Is ( 2.2k ea, 171k/2), and usually the MRM/HBC bank unless it's a really light wave, so that's 3 HBC I's( 17.5k ea, 52.5k/2) and 78 MRM Is (2.2k ea, 171k/2). Ignoring the starships I'm using as cannon fodder and attempts to reclaim, in just turretry thats 790k in materials that are spent repairing for wave defenses, roughly. Waves are landing roughly every 10-12 minutes gametime from the advanced logging, and they're Mil I boosted. If the sieges and leeches bite it on defense that's another 800k since they're not repairable and need to be rebuilt.
My current econ with Harvester IIIs is metal: 1132 - 211 = 921/s, and crystal: 1462 - 202 = 1260/s, so total of 2,181/s. My build queues are currently mostly empty except for a bomber being built to replace the handful I lost taking out a fortress, so that's pretty close to my max econ.
As my econ stands, to get 790k in materials to rebuild after a standard wave takes 362.21 seconds, about 6 minutes. This means half my current econ (with Harvester IIIs) is being poured into/saved for defenses. That gives me another 5 minutes worth of econ to work with the fleet, which is roughly 654k in mats, not counting the crystal -> metal conversions which my bombers give me fits over. Ignoring the corvettes, which are .9 of my 1.7mill fleet, that leaves me 800k in fleet to rebuild if they wipe, which means ~1.2 waves worth of econ.
I'm sorry, but I'm having a very hard time seeing how y'all have this huge economy at low planets to the point that harvesters are broken. Yes, I get some feast-times too when my fleet does everything right and I can get a bonus, but really in my games that's just a bank for later so I can get the fleet out again, or maybe sink a bit of materials into other goals, like a transport fleet or some additional starships. When I take another planet for resources (Econ or Harvester) the AIP goes up and my defensive costs go up too. In theory if I can soak the defensive costs my offensive costs go up (hopefully to the point where they go back down later because the fleet ball can handle things without wipes). Sure I'll max off to 999s but that's barely enough to refleet with, and that's a mostly MK I fleet, and it'll be awhile before I return to it.
*scratches his head* I must be doing something severely wrong here...