Who even dual boots Windows anymore? Fast boot is on of the whole points of Windows 8. Leave it alone and use VM's like normal people do in 2013. And "cleanliness"?
I don't dual-boot now that virtualization has gotten pretty good, but I did dual-boot back in the day (this issue with altering the disk state during hibernation has been around for as long as hibernation existed, which predates VMs).
Dual-booting is not the reason I disable fast boot. As I explained, fast boot is designed for non-SSDs, and there isn't a substantial performance win by doing it on a SSD.
As for cleaniness, there are benefits to doing a clean shutdown. What if a driver or service is buggy and leaks memory? That will not get reset by a faux-shutdown. What if a bug breaks the internal state of a driver or service? That will not get reset by a faux-shutdown. Oh, and I wouldn't advise changing your hardware if you did a faux-shutdown.
And finally (and most importantly),
fast boot just doesn't make sense from the perspective of a power user. Microsoft intended fast boot to replace both shutdown and hibernate in the UI. You'll notice that hibernate is missing from all the shutdown options. The dialog that disables fast boot can also restore hibernate to the shutdown menus. For a power user, separate hibernate/true-shutdown is far more useful. Most of the time, I use hibernate because why save only the system state? I want the user state saved as well, so that I don't have to reopen all my programs, scroll back to where I was, etc.
That is a vastly more significant time-saver. There are only a few situations where a full hibernate (vs. the half-hibernate of fast boot's shutdown) isn't the best way to cut power, and in all of these situations, what I want is a true shutdown. For example, if I'm changing hardware.
Fast boot was really intended for the stereotypical technophobe who jots down instructions when you teach them to use the computer. They're people who have been taught long ago that when they are done, they need to close all their windows and then go "shut down". These people never select hibernate and don't really understand what the difference is between sleep, hibernate, and shutdown. I have family members who are like this. So Microsoft simplified it by merging hibernate with shutdown into something that really does not make sense for power users like us. People who browse forums like this are probably far better served by restoring the hibernate option, and getting rid of faux-shutdowns. I use sleep, hibernate, or reboot (which, BTW, uses true shutdowns) almost of the time, and the few times I need a shutdown are all situations where I need a true shutdown and not a half-hibernate.
I don't care if fast boot is a touted feature because I'm not the target audience. Those new tutorial boxes that pop up on the screen teaching you about the corners and how to use the OS are a touted feature too, yet killing them in group policy is one of the very first things I did when I installed 8.1.
