"Perfectible" is an adjective (as I'm sure you realize) that means "capable of being made (to be) perfect." Moreover, perfect comes from a Latin root meaning "finished, complete." Once something's complete, that's it. There's no such thing as "more complete." I know "more perfect" has a long and illustrious past, but I'm trying to hold the barbarians at the gate. I fear that "should have went" and "should have did" (etc.) will also become standard in a decade or so. It just makes me want to vomit.