I use my birth name for the same reasons as Phil Cooper, but also because there are so many of us that it's confusing enough as it is. Guess who one of my favourite film directors is! Many decades ago, my first wife complained that she (and my mother) called me David while the rest of the world called me Dave (apart from a few who still called me David R), and did that mean I was a different person at home from in the world at large. I'm more concerned with the spelling of my surname.