Killings not too difficult for any class. You can kill, or you can kill efficiently. That's the difference with all classes. As far as marauders go, survivability does take skill. There are very few sentinels (I don't say marauders because currently there aren't any) on my server who are too stubborn to die. I'm proud to say that I'm one of them. I'll say it like I've told everyone I've encountered who falsely believes this class is loleasy to play, try it yourself and see how you do with it.
Oh Neo I know you like to disappear whenever someone out plays you. Is that what you call skill? I don't have an oh crap button as a sniper. If I attack someone and they fight back I have to figure out how to out play them not push a button for an instant escape. Also much of the time you don't even have the brass ones to continue the fight, but will instead run for a heal. Maybe you can call it smart gameplay, but it is an advantage that not all classes have. NOT SKILL. Really the skill came when you found out which class had the damage, the survivability and the utility all into one....a skill in picking a class.
Sorry Marauders and Sentinels just have to memorize a few buttons, namely the ones that let you get out of everything instantly and then a few you can mash for attacks.