I am in the early sessions of running a science-fantasy Pathfinder game. I'd like a grittier feel to the game and came across the "Wounds and Vigor" variant rules.
For those who have used these rules, how did they affect gameplay? Were they worth the added complication, and are there other considerations I'd need to account for to successfully use this variant of the rules?
EDIT: I am going to narrow this question a bit. What are the positive and negative affects on the game mechanics for choosing to use the optional Pathfinder rules "Wounds and Vigor"?