I can add that I have tested using the ioatafamily.kext without any plugins, and I still got the iokitwaitquiet error. While if I just remove the ioatafamily kext then I don´t get the iokitwaitquiet error and the boot time is about 40 seconds shorter, but then only my usb disk works.
I it seems that using the ioatafamily kext is unavoidable if I want my internal disk to boot... at least I haven´t found any other solutions so far.