Yes, the clarity shortly after waking is noticeably clearer when doing biphasic. And for sure it is my preferred system, but I don't feel like I am the master of my time currently. I have a full time job and two very noisy babies ;)

Waking before sunrise I would highly recommend. Forgot to mention the instinct of children around this one. It is very natural for us to wake the moment the light of the new day touches our skin. And there is something really special about the colours & energy of the sun when it first hits that horizon line. It will enhance your energy all day.

I am a sun-gazer too. But that's a whole other story...