Well, I do some fixes in my DSDT which (to be honest) I am not sure are really of any practical use. For instance, I check which kexts are loading and then look to see if there are any that might need a patch.
One of these is the AppleLPC.kext, that used to considered to be needed to load for proper power management and so I use a patch to inject the device ID of an Apple LPC device to make the kext load. Similarly there are other traditional fixes to the HPET device and to the RTC device to handle interrupts and so I usually do those fixes, and also include some fixes under the USB devices for helping to ensure there is enough current during sleep.
I think that maybe some of those traditional fixes may not be needed any more with the Z77 boards, but I know that those fixes do not seem to do any harm so when I do my edits I include them anyway, because if they even help in a small way then why not use them? I would be interested to read any articles about what really is needed now but there is not much information of that sort around on the internet.
Anyway, what I would say as a general rule now is that if your system works then do not add any more fixes until you know what you want to fix! I also recommend though (if you are really interested) is that you download text wrangler. Text Wrangler opens dsdt.dsl files and has a very useful feature for comparing two documents ("Compare two front documents") and showing the differences and then letting you apply changes from one document to the other. That feature is really good for comparing your DSDT to someone elses for the same board and helps you to work out what fixes to use and how.
This post though is getting far too geeky so I must stop now!
I hope in some way it helps, but I think you have done a very good job of fixing your system already. The next step for you is probably sorting that front audio problem and that solution will be in editing the kext, not the DSDT.
(except good quality sound on front panel audio).
