With that chip you should get around 2.5x faster single-thread performance (mostly due to the higher clock speed), and 3 more cores inside as well.

Yes, the higher performance is rather appealing. Of course one of the reasons for the success of the raspberries is the low energy consumption, but sometimes it is just to slow. A little reserve really would be good for media centers or also if you want to have a small server solution.

Of course best would be some device with low power consumption when less work is to do and which can go to full power if needed. Multiple cores would be good for that, if the device could deactivate unneeded cores or even reduce the clock speed.

I am looking forward for more power saving devices, since servers which run all the day should consume less than today.

There might be opportunity for lower energy, speculating if the SoC has better dynamic power abilities, and even without it, can finish it's work earlier and go back to deep sleep longer.

curious to know how the port is implemented - if it's wedged in to the USB bus like on the pi that has performance implications.

AFAICT it's a direct bus connection, no USB bridge. That said, most Gbps Eth are capped around 500Mbps by said bus.