The USB to SATA adapters found inside these types of things are much smaller, cheaper, and more readily available. They also have the advantage of being bus-powered and a USB cable is a lot easier to bend into position than a 40-pin IDE ribbon. Of course, adding USB host to an empeg may outweigh the price advantage...

I remember the turbonet ethernet cards for Series 1 Tivos achieving 22Mbps without DMA. Even if only something like 15Mbps is possible, that's a whole lot better than 10Mbps.