Sursroemming: OTA upgrade does not wipe out your current files, it's purely updating ur OS with the changes the upgrade brings.....whereas flashing I believe is pretty much starting from scratch, like installing a brand new operating system (or at least the same feeling).....and hence makes ur device behave like it has just been brought to life.....provided u flash the emmc as well (the 32gbs or 2 gbs in ur n900)......