Quick note on Arcanists.
Possible interpretation of the Pact issues: you can gain a total 'bonus pool' up to your level, but you can only use 1-10 points of it at a time. (Could be wrong, though.)
There are five "Aspects of Power:" Bounding Step, Daunting Visage (think Gandalf in FotR movie...), Eldritch Dart, Master of Heat and Flame (fire melee attack,) Wound Mending (personal healing.) All require con checks to activate. Greater Aspects give bonuses to your aspects; Ultimate Aspect (at lvl 20) doubles your Master rating for spell checks.
Int supposedly helps 'manage spell energy and channel it into the world,' but the only benefit I've seen from it is that it gives bonus damage to offensive Aspects. Possibly the typo in the Magic rules claiming Int added to DC of magic checkwas supposed to say that Int bonus was added to your roll.
He may not hold his own with the other classes, though... it's noted that the Arcanist should not be converted out of IH if there is another magic system, as he's at a disadvantage. Since the others are on par without gear, and have to be reined in if they *get* the magical gear, this implies to me that the Arcanist is weaker.
ALso: someone asked if IH used the NPC classes. They are hinted at (for example, it's stated that a local militia commander would most likely be a level 3 warrior,) but I didn't see them printed anywhere.