Ok, so if you're needing to capture uncompressed HD video from your Xbox (360 I presume?), then why would you need a drive speed, for recording, that's at least 5 to 10x the speed of the unit that's creating and processing the video output?
apparently you do not understand how blu ray discs store video data and how the players actually play back the content. or how the xbox, or any video card or video playback system for that matter, generates HD resolution video from games or disc. the data used to generate the video stream and the data actually in the video stream itself can be, and usually is, vastly different.
If it's for live streaming that he's seeing frame drops, that's understandable, unless it's enough to cause hiccups. You're not always going to see something HD in 1080p running at it's peak framerate, constantly, through the entire stream.
what are you talking about? video over HDMI (what we are talking about) has a constant framerate. there is no "peak" framerate. it does not vary for a given resolution.
read this pdf
for starters (the adobe hidef white paper from 2004). it explains why a fast RAID system may be needed for real time uncompressed HD video storage. 100-160 MB/s sustained write speeds are needed to capture uncompressed 1080 HD in real time depending on the format/fps. again, that is sustained
write speed, not burst.