If there is serious wear, a cliffy won't do much. You need to repair it first with bondo or wood repair stuff, build it back up, or the cliffy will dent and fold and look like crap soon after installing.
They are a great product, but they require prep on bad scoops. A lot of scoop damage on Sega/DE, more so on DE, are deep, and cliffy's won't even cover them, as they seem to wear much worse than b/w games.