This is a more broad question than just going to Mavricks. Is there a reason to NOT just upgrade and to do a fresh wipe and install of Mavericks? Does the backup retain "bugs" and "errors"? I think I'd read in the past it does keep all the "character" acquired such as errors that stay somewhat hidden from the user. I'm not looking for "My Mac SEEMED better after..." but actually proof one way or another on the matter.