Sony will only stick to their products and quite often the official line too. They will not guarantee compatibility on any other brands or generic remote controls either - which i doubt they would know anyhow.
Unless another forum member has this exact hifi system and can confirm models of other remotes that work - or your willing to experiment by purchasing different remotes, then the only way i can assist you is see if other Sony remotes from similar systems will work. As you rightly say, the IR codes will likely be the same, but cannot be guaranteed especially if products are rather different.
