I'm about to pull the trigger on an MBA i7/8GB/256GB but I was wondering whether I should wait for Mountain Lion. Or will Apple give me the discs when ML is available? Will the installation wipe out completely the current OS leaving the MBA like a genuine new laptop shipped with ML, or leave it like if it's been "upgraded" (like a Windows machine, with consequently slower performance). I would like to do a fresh install when ML comes out.