Just struck my mind recently that some worker balance on 2x speed servers are really bad compared to 1x speed server.
You get the same RP for research worker, but on 2x speed servers you make RP twice as fast. So worker should give RP twice as often also, in current state its really not balanced and you don't see many top teams trying to get this worker.
Cash worker is the same. You should make 2x cash in an hour, but the worker gives the same cash as on 1x speed server, so again unbalanced.