OS X's "Send all traffic over VPN connection" seems to be failing

Or my expectations are wrong.

I expect that checking the "Send all traffic over VPN connection" will send not only browser http and https traffic over my VPN connection, but also helpd, terminal, misc. application, and well, ALL traffic. This is not true. By watching network activity, it appears traffic is going through both the VPN and default connection.

Is there an error in the system, which I can correct? Is my expectation wrong?

The thread A simple fix for a 'Send all traffic over VPN' issue says :

In setting up a VPN on my OS X Server at the office, I was having trouble getting the OS X client option "Send all traffic over VPN" to actually do what it says. In fact, the setting appeared to change nothing on my client machine. After much googling and searching the Apple Discussion forums, I couldn't find anything specific to my issue, so I wanted to reveal the solution here for others to enjoy.

Simply go to your Network Preferences, open your Network Port Configurations, and drag the VPN entry to the top of the list.

This seems to force all TCP/IP traffic over the VPN no matter what the "Send all traffic over VPN" setting is, but only when you are connected to a VPN. I don't think this is an ideal solution, but at least it allows me to tunnel all my traffic while traveling.

I haven't tested specifically, but if you're looking at the network throughput, you're seeing what I'd expect.

Suppose, for example, you transfer 100MB from some random internet server. The server's packets are transferred entirely over the VPN connection, so you'll see 100MB of traffic going over the VPN interface. But the VPN connection itself is routed over the default interface, so you'll see maybe 110MB (100MB + overhead) going over the default interface.