Other than the things mentioned in the FAQ, using a USB to SATA adapter inside the empeg is probably going to be easier/smaller than converting the existing IDE interface to SATA. We also wouldn't be stuck with a maximum of 2 CF cards in a solid-state empeg.

I don't imagine USB 2.0 speeds would be possible, but it may be beneficial to add a 10/100 USB ethernet port. I don't think 100 Mbit is achievable, but anything over 10 Mbit would be welcomed.