While it's more expensive the native gigabit ethernet ports are nice to have. I use my RPi as a dev server/file server and I sometimes have problems with the USB based ethernet going brain dead and needing a USB bus reset (I keep a USB wifi adapter plugged in so I can still SSH in). I don't really fault the RPi since I'm not using it for what its designed for (hell, the ARM CPU is actually the coprocessor to the GPU[1]).
I think I'll pick one up. It will make for a much better dev server/Time Capsule clone/AirPlay server clone/router than my PI, and then I'll have a free RPi to use as a micro-controller.
I have one of these (mk802ii to be exact) as well as a raspberry pi. I run lubuntu on the mk802 and it does what I need it to do. However, that doesn't include fast networking and/or video playback.
Personally I would happily fork out an extra $50 to get 2x gb ethernet and decent video performance.
http://osdir.com/ml/fedora-devel-list/2013-07/msg00754.html