Shadow Pounce is really the only thing the Marauder gets that's at all worthwhile. And you sink some prereq feats as well (Mounted Combat...). Shadowlords, OTOH, are made of win all over, except for the high (but not entirely useless) prereqs. Shadow Pounce is the best of that class, too, but the rest isn't to be neglected. Who wouldn't like to make a Reflex save to just not die, at all? Spells are fine, as well, and Sneak Attack trumps Sudden Strike in every way.