Al parecer y si mi ingles no me falla no teneis k esperar mas los k esteis en 2.80 o 3.03 para usar el de n00bz, pork al parecer no deja restos de ficheros ni nada por el estilo, os dejo el texto en ingles:
After some exhaustive testing, we've now come to the conclusion that there is no unnecessary wastage of flash space during the 3.03 downgrader process.
This means that our belief that there would be a need for a "flash cleaning" application was wrong - you should be able to upgrade and downgrade your PSP at will, with no serious problems except for the ever-present small risk from any downgrader.
Un Saludo