You are correct. If you disconnect the tablet from the base while the base is connected to the dock, when you reconnect the tablet to the base, the SB does stay on battery power. I imagine that will be fixed in another update. I'm just happy my USB devices and monitor are stable. I can handle disconnecting/reconnecting the dock connector when I reattach the tablet to the base. Before I had to actually reboot the machine to stabilize the dock.
Here's to progress!!!
-Blake