Mac to Mac connection speed via ethernet?, Tools?

There is a way to connect two Macs via an ethernet cable. You make sure sharing is turned on and one Mac mounts the other as a volume.

No problem with this, though I am curious as to how fast this connection is…is it at Gig/E speeds? Does anyone know of any tool to measure the throughput on this “networked” volume?

I tried to use AJA’s Kona System test app (which is great at measuring hard drive throughput on a system) but it won’t recongize the mounted volume on the other system… Ideas?