First of all, there are no legal implications for updating your firmware like that. The license restrictions are for SELLING the drives not for building them for your own use (which is what you are doing essentially). If you want to modify that drive and ebay it then you will probably run into legal trouble.
Anyways, which drive are you talking about anyway? I dont think it is a rebranded unit as Philips tends to make the chipsets themselves.
Kristopher