I like Romanian complex. It sets me up for reinforcing the Eastern Front if I do a DOW Russia 1st turn as Germany. I can exploit weaknesses behind Russian enemy lines using sea assaults with transports if I need to bypass the front lines Russia has set up against Russia and send units to take control of the IC two spaces away from Russia.
after dropping 30 IPC’s on a complex and then purchasing a navy to do sea assaults, I don’t see how you will have enough bodies to make a strong push into Russia. That’s the entire argument against purchasing the complex. It distracts from the main objectives.