WI: Konstantin Pavlovich becomes Tsar of Russia?

IOTL, there was a significant movement within parts of Russia's elite to put Grand Duke Konstantin Pavlovich as Tsar of Russia, by deposing his more reactionary brother, Nicholas, in an armed uprising, now known as the Decembrist Revolt. The revolt, however, mostly foundered, because Konstantin showed no interest in becoming Tsar, preferring to instead remain as governor of Poland.
But what if Konstantin had accepted to become part of the Decembrist conspiracy, and had also managed to dislodge Nicholas from the throne?
Would he maintain Poland's autonomous status for longer, thus possibly butterflying away the November Uprising of 1830?
How would his comparatively more liberal ideals translate into his internal policy?
What about foreign policy? Would he still intervene on behalf of the Greeks in their struggle against Turkey?