[Cyclop]

Using the sanity rule would add some flavor to the game as the campaign grows. No one will really notice or have any side effects from it during the earlier lower level stages but as the party gets to the higher levels 8-12, you could then see some changes or issues a person or party might have to deal with due to the long term effects.
The good news is the players really don't have to do anything for this rule other than role when I ask for a sanity check. I can carry the burden of the player tallies (along with exp). I think as the group plays more together it will add a bonding effect.
I have never tried it with D&D but I have used it during a Cthulu campaign, Boothill game and another sci-fi horror game.