Light sided Sith could simply view the Empire as the only real way to have stability in the galaxy. I imagine that they would view the detachment practiced by the Jedi as counter-productive. How can one profess to guard and value anything, when they cherish nothing?
Light sided Sith would probably use righteous anger and justified hatred to, in their minds, do far more to protect the people of the Empire than the droid-like emotionless nonsense of the Jedi serving the corrupt republic.
There's far more to emotion than just hate and anger. Rather than being driven by ambition for power, a Sith could put his or her life on the line for the sake of brotherly love for his her her fellow citizen of the empire. At that point, seeking power is more just a means to an end and they would view their assuming leadership not as a right or privilege, but as a sacred duty.
Actually I've noticed a lot of times when you do the dark side thing, your teacher/mentor/whatever will not be happy. Like for example, if in Black Talon yo choose to kill The General, Grand Moff Kilran will say "It's too bad The General couldn't be taken alive." meaning HE'd have rather you did the light side choice.
Also, and this I won't give details as it's more spolers than a simple level 10 flashpoint... but the Imperial Agent storyline I beleive Light Side is HIGHLY loyal to the Empire, more so than I think a Dark Side would be. Dark side seems to me would do exactly as they are told good little sadist sheep. Whereas the light agent takes initiative, loves the Empire, and wants to make the Empire stronger and realizes to do that you can't go around shooting everyone like a madman (granted, I've not played a dark agent, so I don't knwo that's how they are, but that seems to be the going thing for dark side on Empire... bloodthirsty insane sadists.))