Is it better to work with a demon you know rather than an angel which you don't know?

As you say, there are pros and cons of the demon/angel approach, both are difficult and a risk but you've got to do one. It almost doesn't matter. What worries me most about your comment is the 'unofficial policy'. I don't like the sound of that. Policies are either something you stick by or you don't. And the 'unoffficial' bit sounds dodgy to me. The very fact you asked the question makes me feel like you are questioning whether you should adopt the unofficial policy or not. Will it put you in an awkward position if you don't?