I liked this part: Critical hit chance/damage - Melee = Dexterity, Ranged = Perception, Magic = Intelligence
I don't really have any favourite stats or stat systems, as long as they are implemented well in the game. No stat sucks, per se, though I generally ignore Intelligence for a warrior or ranger, and don't play mages as a main character. D:OS will have 4 of the 6 skill groups being magic, but that may not mean much since we don't know the size of any of the groups yet. Who knows, maybe I'll finally play a mage character in a Divinity game...
blocking - Dexterity / Speed or maybe Perception
That 4 out of 6 groups thing you was actually a miscommunication - we're still adding skills & spells and the final grouping isn't really decided yet. I doubt very much that it'll be just 6 groups, given the quantities we're working with now.
Critical hit chance/damage - Melee = Dexterity, Ranged = Perception, Magic = Intelligence
I quite like the idea that critical hit is decided by different stats depending on the type of damage, but you have damage & chance - would you let them be derived from just one stat ?