The Combat Fury or whatever of the Marauder is not working properly -- meaning that you do not get the bonus attacks you are supposed to receive. Otherwise, they were pretty neat. I'm trying a Weaponmaster out now in my current playthrough to see what they're like.
I preferred the Sith Lord -- more Force points and more powerful Force punches (so to speak), your alignment bends your party more towards your dark leanings (and thus they easily get the bonuses of being max darkside for their respective Jedi classes), Crush Opposition erodes opponents' "to hit" and such, etc.
But, really, Force Crush is going to be your bread and butter after you return to Dantooine, which you get no matter which Prestige class you picked as a Darksider.