Of course another Ethernet port would be nice, but I think that you will be equally pleased with the performance using a usb-to-Ethernet adapter.
There are other boards out there (which we shall not discuss in-depth because it's against the forum rules

that have more than one Ethernet port, but have no VGA out, run on slower CPUs (think 400 MHz) and cost more. The Fit PC's magic is its versatility and performance - I have successfully used Fit PC Slim as a NAS gateway and got the 100 mbit/sec from the USB disks attached to it.
I plan to buy a Fit PC 2 as a home gateway as well - you don't need more than 2 interfaces and the Internet interface does not need more than 10 mbit/sec (Unless you're lucky and get fiber connection to your home

which means it will live very well with a USB1 Ethernet adapter.