ok GWH then when people ask where i stand i'll just say i am an atheist - and when they ask why i can be so sure that no god exists i'll refer them to your venn diagrams and go into a long discussion about how i am actually an agnostic but since agnosticism can be grouped under atheism then actually you see i......... come on.
there are weak and strong versions of agnosticism too but having to decalre your camp each time could get irritaing couldn't it?
i think it's important to be clear since as you stated 'lack of belief' and 'belief in lack' are so extremely different. atheist and agnostic have specific meanings in the common venacular, i see no reason to abandon them unless the goal is philosphy final.