Sadly, nobody has discovered a proper fix for most of these issues. I've described a couple of solutions to specific cases above, but they aren't really the core problems here. Fortunately, there are still some workarounds that might work for a few users, at least until the real issue is resolved. The easiest option is to simply switch from Push to Pull with a reasonable interval. This will have your phone polling the server for updates, which is more processor and data intensive, but it should be more reliable. Even though this consumes more power, it certainly won't run your battery down as quickly as the sync error loop. Take note, some people are saying this still isn't reliable for them, so pay close attention if you're going this route.
The next fastest alternative is to switch to using the IMAP protocol. Plenty of corporate servers support this as an alternative to Exchange. You'll be losing calendar support and a few email features, so this definitely isn't for everybody, but it is an option. Assuming this option is available to you, it's still free and the trouble to set it up is minimal.
Finally, I have to mention - no, recommend - an option that won't be very popular. As I said earlier, some people are using 3rd-party apps with custom Exchange support. They aren't cheap as Android apps go, but they work and give you a lot more than the stock Mail app is ever likely to provide. This is one of the advantages of Android, you can usually replace the pieces that aren't working for you. I haven't personally used either of these apps, but a few people in the forums have mentioned them, so I'm including links to NitroDesk, Inc. and Emtrace Technologies, Inc. Both vendors offer trial versions of their apps and currently charge $20 for an unlock key that works across their respective product lines. If you want to run KitKat and it's absolutely vital that you have working Exchange support for your job, it might just be worth the investment. Even if you only run the trials for a bit, you can probably make it until Google gets its own code fixed.