Do characters like bard, sorc or other Cha dependent chars have a better role-playing experience than other classes? If I play a monk for ex will my bluff skill eventually get me the same game experience as a bard?
IIRC there are sometimes different Dialogue-Options, and occasional you can even avoid a bit of combat or get a better reward, but the core-experience doesen't change.
Edit:
With a very high Cha/Diplomacy Skill you can broker a real Peace between the Lizardmen and Highcliff - but it changes nothing but a few lines of Dialogue later in the game.
In SoZ you can convince a Shop-keeper turned Necromancer to stop raising the dead and open her Shop once again - and so you gain Access to some nice Spells and Items.
Also sometimes in the OC and in SoZ you can intimitate a gnome-mage to flee and leave his buddys without a arcane Caster to fight you.
Yes, having a main character with high diplomacy skill is an advantage if you like roleplaying. It's not mandatory, but I would recommend playing through the game at least once with such a character.