360 DVD data limit is 6.8 GB

[NJ5]

The PS3 reads at 9 MB/s. The 360 reads at more than 11 MB/s, as anyone can see by installing a game to the hard drive.

NBA Live 09: 6.3 GB in 9m7s (or 11.8 MB/s)
The Force Unleashed: 6.6 GB in 9m47s (or 11.51 MB/s)

These are double-layer games.

http://www.gamespot.com/hardware/blogs/hardware-insider/909185655/26656232/xbox-360-hard-drive-game-installation-testing.html