Even if only something like 15Mbps is possible, that's a whole lot better than 10Mbps.
IMO, if a sync is going to take so long that 15Mbits/s is better than 10Mbits/s (and
remember that the player software can only sustain about 6-7Mbits/s, it can't even saturate 10M Ethernet), then it's long enough that it's worthwhile opening the player, and using one of those USB-to-SATA adaptors on a real USB2 PC, where with a modern drive you can probably nearly saturate USB2 at 480Mbits/s (60Mbytes/s).
USB host on the Empeg would be a neat hack for various reasons, but faster synchronisation isn't one of them.
Peter