I'm really not a fan of the way you are encouraged to super-specialize planets.
If you have 2 'generic' planets, each with +100% research and manufacturing bonus and 10 base income of each (50% split), you get 40 research and 40 manufacturing total.
But if you have 2 planets with +200% research on one and +200% manufacturing on the other, with 20 base income in research and manufacturing respectively, you get 60 research and 60 manufacturing total. There's a huge (50%+) advantage from specializing right there even before you start taking into account synergy bonuses, planet event bonuses, starbases, capitals, etc. which will make the difference even worse.
This also means that if you have less than 3 earthlike planets (1 income, 1 research, 1 manufacturing) you have an almost insurmountable disadvantage in efficiency. Additionally and somewhat disappointingly it also largely minimizes the effects of the planetary events. Even a rare +50% bonus isn't that significant once an earthlike planet is developed. (80 turns in on my current game and I can get 200%+ bonuses)
This phenomenon is a result of the combination of the 'governance' screen and the percentage based boosts of basic structures. If basic structures provided flat boosts or if the governance screen was disabled, planets could gain advantages from specializing but not to such a dramatic extent.
Honestly I think the ability to change planetary base income into different resources on a totally freeform turn by turn basis causes more harm and micro than it provides gameplay benefit. I know you guys were plugging it in the design phase but IMO it hasn't worked out.