Updated from 10.10.1 to 10.10.3 this morning. All went well!
Info:
• Clover Bootloader
• Running ASUS Sabertooth Z77
• GTX 680 with nVidia Web Driver
Steps:
• Cloned the drive. I used SuperDuper, in case something goes horribly wrong (spoiler: nothing went wrong)
• Copy AppleHDA.kext from /System/Library/Extensions and copy that to /EFI/Clover/kext/… because there are reports of audio needed fixing
• Made sure I have the newest Clover (as of this writing, it's r_3193).
• Ran the Combo Updater.
• Booted back into 10.10.3 (first boot took a little longer than usual)
• nVidia web driver popped up with an update notification, so I went ahead with the update, reboot again
• Done.
I never turned on TRIM for my SSDs. So, I don't bother turning on TRIM for 10.10.3 either
Everything is working perfectly. No broken stuff, audio is working as usual, no issue with my displays/GPU. iMessage is still active.