I tried Economic Starbases in the DA Beta over the last two days, and they're actually pretty nice, because of the new Power Plants. What's more, they combine well with Super Hive. The AI is not very good, though, in the beta, so it's still hard to tell how they'll do when you've truly got aliens breathing down your neck.
I was reasonably able to get Econ Starbases to encompass 5 planets, doing comfortably over 100 ip apiece (that's a conservative estimate), and I could reasonably get to 17% boost through SB upgrades (25% is too ideal). That's 100*
.17 = 85ip extra per turn, of which 43 is free.
To compare the cost, such a starbase takes 6 constructors, at ~150bc apiece, plus we have to add ~900bc average overhead (the price you pay up front if you're not Evil), for a total of 1800bc + 15bc/turn maintenance. So the break-even point for these starbases would be after 1800/(43-15)= 64 turns, if you're speaking purely in terms of free production. But if you take into consideration the paid production capacity, that break-even point is 1800/85 = 21 turns. That's really low. And if you're Evil, you can chop all those break-even times in half, because you're not paying the up-front fee. Then you can turn around and re-invest that capacity for more constructors & social improvements, for more free production.
I'd say Econ's are definitely useful in DA, but I seriously doubt spamming 12 SB's on a single planet would really turn a difficult game around. Unless you're Evil. It's hard to say for sure, though, because I have yet to play a difficult game on DA beta.
