I disabled it last night, and the HD access has been much better.
Do I want to disable it? No. Does disabling it make my system more responsive? Yup!
I'm not talking about about the odd thing here and there, I've noticed a big difference. Its no longer loading things into RAM when it shouldn't.
It's clear that from the replies in this thread and from the many many more on Google that something its doing is not right. The idea is great, but when its loading things and getting in the way of me doing what I want to do now, there are issues.
I'll be honest, I wasn't expecting it this far since release.