only on multi homeworld actually. I don't think the new harvesters are extremely overpowered in a regular 1 homeworld game. they just feel good.
I'm playing a game with them right now, and yeah, they feel really good. They feel so good I decided to work some things out myself. I know this was discussed elsewhere, but I played some, went back and reread the numbers, added some assumptions of my own...
1. The aforementioned homeworld. Homeworlds have either 12 or 13 harvesters. Going from 20 to 73 each is a 53 res/sec increase. Multiply by 12 in the worst case and you have a free 636 res/s additional income that you can unlock as soon as the game starts.
2. Did I mention you can unlock it as soon as the game starts? At least with econ IIIs you have to cap a planet first.
3. If a planet has 4 harvesters, it's automatically better. Assuming 2/2 for simplicity, you get 146/146 m/c per sec. How is that better than 160? Because you haven't factored in the additional resources from the command station that you have to place. Econ Is give 30/30, bringing you up to 176/176. Mils and Log Is are slightly worse, but bring other benefits. And if you unlock higher-level command stations, the margin just goes up.
4. You know planets with ARSs? Those tend to have 5-6 harvesters, and you have to take them
. Even if core shield gens didn't exist, they'd still be well worth the AIP for the ship and the resources. That's an extra 70 or 140 res/s per ARS planet, of which there are usually... 5 or 6 across the game?
5. Advanced Fac planets spawn with additional harvesters too, iirc? Or maybe I'm just getting lucky.
6. Previous discussion talked more about the average number of harvesters per planet, not counting homeworlds. I think it was 3? Well, you can skip 99% of the 1-2 harvester worlds, but you're predisposed to capture worlds with lots of harvesters.
So basically, the new harvesters are almost strictly better than econ IIIs even in a single-homeworld game. They give you 600 income completely free from the start of the game and still outperform econ IIIs on average in the rest of the game. And you don't use up a command station slot. That last bit alone should be cause to make them a good deal worse than Econ IIIs (you can still get lots of income from your chokepoint world that has a Mil III), but they're still better. It's just... wow.