Compared to mages they are absolutely terrible because of the stunted mana pool. It depends on your gear but I'd expect anywhere from 2 - 5 MCC around level 55 (I could be a bit off).
Paladins are obviously better because they start off with twice as much intelligence as a samurai, though it's still nothing like using an actual caster class. You'll notice that you don't rely on your heal charm as much because you have much higher life and also your regen times are much shorter (because you don't have as much) but it can be really really slow at the later levels
