Be/ keep / stay in touch

To me all three mean different things. Let's be in touch I say this to someone I've never before met, but during the course of our conversation an important matter emerges which affects us both. It seems important that we maintain contact. Let's keep in touch I say this to a colleague with whom I have worked for several years, but our future paths are about to divert. Let's stay in touch I have just attended a conference of people working in the same industry. many of the participants were new faces to me, some were old friends. At the end we all appreciate that we have gained a lot from the meeting, and someone says 'let's stay in touch'