Well, from personal experience and from post i usually read, Juggernaut is not far behind in DPS from a Marauder if specc correctly.
So there you have it, you can choose a Tank / DPS class (Juggernaut) or a full DPS class (Marauder) that doesn't go to much far ahead from the other, but it can't tank.
Juggy's tanking is also a new experience if you tanked as a Powertech. They can take a larger beating, but have a struggle keeping multiple mobs in aggro.
Your choice really. A really well played Marauder can actually top any class Dps, but they are rare