Let me clarify that PPTP thing a little. If you have PPTP connection to localhost, like to a JanusVM appliance, you aren't going to leak. Why? Perfect line quality. There is no bad routing or external travel required to communicate to yourself. So PPTP isn't inherently terrible, it's just terrible for privacy and anonymity when you are using to talk to computers outside of your localhost or home network because it is so fragile.