I find Chapter 7 to be easier except at the boss. (well this may not help considering I know the level completely)7 is more difficult than 8, in my opinion. But it's been a while since I've played either of those chapters, and neither were on intensity 9...>.> Er...yes. Though I fear Chapter 8 will be difficult as well.
However chapter 8, I find it harder. Except at the boss. XD