jheoaustin, you could be right. You need a high-quality, low-jitter clock in the prepro but you probably wouldn't need the Apogee's extra jitter-removing circuits. That said, I don't know exactly how the Apogee does its magic so I'm just guessing.
Krobar, in the long "standard digital interface" (or something like that) thread, dr1394 monitored the commands between a Pioneer receiver and transport. As I recall, it had to run something like an hour before the receiver sent a "slow down" command indicating the buffer was getting too full. So, while it's a nice feature, it's possible that most people wouldn't notice the difference. However, if different brands of components were used, with different clocks, it might be more important. Regardless, it's available in the standard and they should all implement it.