[Cyclop]

The rules in the Unearthed Arcana can be quickly summarized as:
Sanity points = Wisdom x 5
Sanity checks are made using percentile against Sanity Score. If you roll below your sanity you could even lose a couple points automatically, or if you miss, a large amount of points could be deducted (1d4, 1d6, etc). Insanity can occur if a large amounts of sanity checks fail over a short span of time (1-2 hours of game time).

In this current adventure, I can guess that some may lose a few points of sanity and a couple could get into the double digits in loss. Keep in mind that the scenes have to be gruesome, unusual, evil, and "mystical" for any of the characters to hit their sanity level. I.E. an elf who hates orcs may not think a beheaded orc is gruesome. However a fallen comrade who gets his limbs ripped off by an ogre could be another story ...

What this could do is help the over all campaign as your sanity can go up as you gain levels and during tranqual times. And it can go down depending upon the adventure routes the group takes.

I tend to like horror and gruesome details so we can give it a try and see what the group feels. Insanity doesn't mean a character is unfunctional, they just may have some "quirks" with demons spawning henchman out of crypts, etc.