To be honest, it's one of the reasons we've stopped Rise of the Runelords for a bit. I have a very small group. Only three players. I have scaled back these encounters to a pretty barebones type of fight, but still manage to almost kill everyone. All I do is fudge rolls. My players have about 60 years of RPG experience (mostly D&D) between them and still get their butts kicked. Highly unmotivating.
Alright, I've known Paizo stuff to be pretty challenging for a long time (a number of TPKs in Shackled City proved that) but this is just getting ridiculous.
5 level 6 characters, with Shalelu level 5 and two level 4 cohorts didn't stand a chance against Xanesha. I'm tired of having to fudge dice in these adventures, scale it down a little bit.
Oh and the map of the clocktower was extremely confusing as to where platforms landings/how the stairs worked for the middle maps. This adventure just got completley 'blah' after Foxglove Manor (which was awesome except for Iesha being a little too powerful in the fight against Aldern). There wasn't anywhere near enough of a focus on the cult, the group is expecting 5 other 'justice ironbriar' like villains to make up the leadership of the cult, and I can easily understand why, the 15 cultist mooks seem just as they are, mooks. Thankfully they aren't too interested in that aspect of the storyline and we can just move on to Turtleback Ferry.
But I was very disappointed with the last half of Skinsaw I must say; shame too with such a strong start.
Edit: Just a note that I put this in Pathfinder General because it's a comment/request for the APs overall. The Gamemastery modules seem to be balanced much much better.