Moderator's Note: The originally quoted post has been removed, but the tone and content of this reply were within the bounds of acceptable etiquette.
At least in the case of SWG and Planetside, those are not comparable projects. SWG benefited from a server source code leak. That's an immeasurable advantage the SWG teams had over any of the CoH emulation projects. And Planetside is an FPS MMO. It is almost certainly fundamentally different from CoH (and most other MMO RPGs) in its architecture. Notably, the most important part of initially getting the game up and running isn't content that might have only existed server-side or PvE mission mechanics or AI entities, but the player entities themselves. In other words, once you get to the Paragon Chat stage of recreation in Planetside you're 50% there, whereas with CoH you're 5% there.
Planetside's history also suggests that the game did a lot in the client that CoH did in the servers that the Planetside private server team can leverage. For example, Planetside was the victim of a lot of hacking behavior of a kind that I don't think would have been possible in CoH, because in CoH the servers were authoritative. In Planetside, it seems a lot of mechanics were implemented locally in the game client in a way the server trusted implicitly. This was more limited in CoH, which is a reflection of the work you would need to do server side to implement things the Planetside guys might be getting for free by leveraging the game client.
From what I understand, and I could be wrong here, I believe the Planetside game client "understands" combat if you talk to it correctly. The City of Heroes client has literally no understanding of combat. That's already a massive chunk of work that a CoH emulator would have to implement from scratch that Planetside is getting almost for free. If CoH's game client "understood" combat then Paragon Chat would probably already be way ahead of Planetside.