I am not an expert....
But in my opinion. I would rather have a ethernet card connect because the USB port shares bandwidth. If you have several things going on it
could slow things down. And the limits are lower than a ethernet card. You might not have to worry about that due to a speed cap. The most simple of cards are 10megs/sec . I personally have cable and usually run 3-3.2 megs/sec and that alone would choke a USB attachment.
Like I said this is my opinion and you should listen to the experts.