I have an oldish first generation macbook air and it is running Lion. My other Macs are all MAV so I would like to upgrade this to macbook air to MAV. The APP store does propose the upgrade but I am not so sure it can pull its weight in terms of acceptable response times. I'd happily test MAV, but I need to be sure I can move back to Lion if the test fails. Has anyone back-installed Lion on a mac after running MAV ? Is this doable ? For the record I still have the install CD of the Macbook air (Tiger and the upgrade CD for Leopard and Snow Leapard. I do not have the Lion install download).