I finally got to crunch some numbers with the new havesters vs economy stations.
I have done calculation of MKIII harvesters vs fullcap of MKII+MKIII eco stations, with an assumption that home has 12 harvesters and each system has on average a total of 3.5 resources.
For the "average number of resources" i used statistical approach using my 3 most recent saves. A total of 101 non-home
systems have been checked, and the average number of resources per planet is 3.88. So i guess it would be fair to set it to 4, but lets calculate for the "worst-case" scenario - 3.5
With the 12 harvesters at home, and not being able to build eco stations until you actually have planets for them, harvesters are superior at the "1 planet" point. Eco stations slowly catch up, but at 13 planets, harvesters generate total of 3392, vs Ecos' 2112. Eco stations just cant catch up with harvesters, given their limit of 6+6. The only situation where eco stations are better is if for some reason you have no harvesters at home.
In addition, unlike harvesters, eco stations have alternatives. Having more logistics and battle stations, even in generally secure areas, is very beneficial. This also means that the full eco station limit is usually reached when you have more than 13 planets.
As such, i believe that currently the eco stations are basically just universallty inferior (with some small exception) to harvester upgrades.
In addition, i generally believe that having MKIII upgrades more cost-efficient than MKII's is wrong, as it very strongly promotes rushing a MKIII. As result, a mixed MKII+MKII, or just getting one MKII is never an option as they arent very cost-efficient. In my opinion, the general rule of diminishing returns should be kept here.
As such, i'd suggest quite a serious re-revision of the econ upgrades system.
Set research costs to 1500/3000 for MKII/MKIII harvesters, and 3000/6000 for econ station. As result, getting to MKIII costs as much. For harvesters, also change their total incomes to 32/56 at MKII/MKIII.
This basically does some adjustments to balance, making eco stations viable again, as well as making MKII's more viable in general.
Suggestion 2 goes further:
Average of 4 resources per system is assumed here.
Research costs are the same as previous 1500/3000 (x2 for 2 kinds of harvester) and 3000/6000.
32/44 on harvester income (so, just a further nerf to MKIIIs, and yeah they are that good); and adjust ECO stations to make 90/150 of each resource.
As result, if you research MKII+MKIII, it costs the same, and if you deploy all 12 eco stations, also gives you the same income. This scheme is what everyone has been doing until this update, this is what i consider balanced enough, and this is what i wanted to stay (almost) untouched.
In general, suggestion 2 brings what i consider ideal balance, where every option is actually viable.
Eco2's make decent money for super cheap cost, but once you have 6, you gotta get higher techs to increase income. You can rush Eco3's for insane income, thats less efficient than using Ecos2's until you actually build all of the stations. MkII harvesters are insanely efficient, in early game they give minimal income so you might have trouble. MKIII's are great for very late game, or on large maps. In general, eco stations are better than harvester, but only if you build them excplusively, as result trading off the chance to use other types of stations.