I wouldn't go that far. Even if they're similar *captain obvious could've told you that* it doesn't mean there aren't going to be performance or compatibility differences between the two. All that we know for sure at this point (at least based on what oldskoolfool says) is that the Pokefami DX and the RDP aren't exactly the same hardware.
You know, this is exactly what I said before, if you care to read back. The NES adapter that is going to come with the RDP is a simple pin connector designed specifically for the RDP. Since the NOAC is internal to the RDP, the adapter itself doesn't need to have external composite jacks.