I've thought about canceling for a month to test that theory, but two things are holding me back.
1) The pre orders for iPhone 4 begin tomorrow and I have many things to sort with ATT over my family plan. Changing unlimited to 2G/limit on two of the phones and keeping it on the others.
2) if I cancel I will be highly PO if I am stuck on the new plan, when i specifically purchased the 3G iPad for the ability to start/stop the plan as advertised. (I personally use over 2G with all my travels and that is without tethering to an iPhone)