Rated 5 out of 5 stars

Great add-on! To make it perfect I miss only one feature, namely bookmark/domain-based automatic switching into private mode.
Thank you for the great job!

This review is for a previous version of the add-on (0.1.0.1-signed). 

This list should be stored somehow. This doesn't looks "private". Or this list should be encrypted...
Anyway, it's not so easy to implement this. And this may be done in other extension: Private Tab should detect third-party tabs in private mode.