By the way, the reliable production of specialist worlds, some could see as a limited production, and thus bad.
I do think they should provide five, but I also think there should be another type of resource. Food. Produced by Agricultural worlds, which General Worlds can be converted into for eight Labourers(nothing else), produce Labourers, and produce 3 Food. 1 unit of food is needed for some Specialist Worlds to function(Forgeworlds and Academies in particular; the others don't seem like they'd need as much, but perhaps should be done anyway for equality/balance or something, except for Shipyards) but not an Agricultural World or General World(since it is assumed that General Worlds provide just enough for themselves). Optional, and debatable in it's usefulness, is Armies needing Food rather than or in addition to Supplies to function. An equivalent for this might be Fuel for Ships, which might be provided by a Fuel world, which just need eight Engineers, and produces Engineers and 3 Fuel...
And of course, to even things out, a Communications Relay might be used for eight Psionics, and do something or other, maybe a new mechanic about getting messages to different sectors or getting ships places quickly or something to do with Intelligence and Morale, maybe(larger Morale boosts and small morale losses for victories and losses in the sector by controlling communications?), and a Military Headquarters, which would do the same thing Outposts do, but for Armies(and cost but eight Military, of course), without requiring Supplies(and the need for Food is small anyway).