I boil my concern about your conclusion to this: Why would a New Romulan join a KDF fleet when KDF fleets are not as far along in progression as Fed fleets? They can get better tier things more easily on Fed side than KDF. House of Beautiful Orion's might get interest, but why would anyone join a tier 1-4 KDF fleet? I see little motivation or incentive, so the likely result will be to join their existing FED fleet and enjoy the hard work they already invested.
Just my view. Who knows. Things change.
Because the most advanced Fed fleets are actually at 80% or more capacity (400+ players) and can't take on the Romulans coming. A change in fleet cap or some other setting would obviously alter this equation.