The Set Tops use programmable DSPs, not ASICs to encode/decode signals, the encryption is programmable, the decoding and channel schema programmable, so the only real difference between the platforms is software, hardware wise they are identical.
So long as el boxen is told what to do and how to do it with firmware no problems, just as your PC can play Quake and Doom so long as the program tells it how. Very fortunately for me it's not rocket science and apart from the actual writing of the firmware relatively painless to appreciate. A digital cable STB is actually a relatively simple beastie once broken down into its' components
