A few pertinent questions here:

• What's the best way to identify core changes and work them into modules? Is there a free alternative to http://www.fontis.com.au/mageaudit/ ?

• How about subversion/git pre-commit hooks to prevent commits to core files? Do you keep Magento core under source control at all?

• How does one prevent changes to core files by mistake -- perhaps a Sublime Text plugin that tells you if you're modifying a core file?

• Is it okay to copy core files to /local to inject a dispatch event for Observers?

...asking for a ...friend. Yeah.