Fact: Modern home equipment (PC, NAS, Router, Switch, etc.) are equipped with Ethernet LAN communication protocols that use 'Gigabit' (1000 Mbps) speed.
Since the weakest link in a chain determines the strength of the chain, the X10 determines the maximum speed (100 Mbps) in the LAN.

For normal radio- and audio streaming, 100 Mbps is good enough. However for making backups (restores) to/from a NAS or to download audio files to a PC or portable audio player, Gigabit is a (nowadays...) benefit.

We can integrate a Gigabit Interface, but that won't help you :-(. The CPU is to weak to manage high speed. Already the CPU is to slow to use the 100 MBit fully....