Toward the end of his excellent article, Gaming the System in the August issue, Mr. Kramer talks of cancelling IFR when the frequency is busy and you have gone into VFR conditions. I have always tried to do this to relieve ATC of unnecessary responsibilities.However, this may be a little different in Bravo airspace. On a westbound flight through Washingtons Class B, I cancelled IFR after passing Baltimore and many of the buildups. The controller thanked me, replying, Maintain VFR, report any changes in course or altitude. A few minutes later I had more buildups in front of me. I reported it, and worked my way through. I have always wondered under circumstances like this if I had returned to IFR what the proper communications would have been in the Bravo air space.