Well, this is a fine mess Apple has gotten us into (apologies to Laurel and Hardy). I used Windows/IBM compatible computers for more than 20 years but switched to Apple looking for elegance, reliability and simplicity. I run my own consulting business and grew tired of having to be distracted from my work to be the IT guy too.
When I switched I moved from Outlook to Mail and was a happy camper. I had to buy a third party conversion software to move locally stored .pst files but I assumed that was a one time deal. With Mavericks my Gmail and Exchange mail experienced the problems you all have detailed. So I decided to go back to Outlook (this time the Mac version). That transition went fine except (as I have noted earlier) Mavericks Mail changed the .mbox attributes on exported mail so those files cannot be read by Outlook. For many this may not be an issue because they do not have thousands of locally stored emails,but it was critical to me. My Exchange server hosting company (Intermedia) was clueless about this, with outdated instructions on how to move locally stored emails from Mail to Outlook. So just like I did years ago, I bought a third party conversion program for $30 to move locally stored emails, this time to Outlook rather than to Mail.
All is well now. I don't have religiously-based views between Outlook and Mail. Each has its own pros and cons. I just need something that WORKS. Since I thought this was Apple's strong suit, this episode has been really disappointing and hope that it is not a signal of a much larger problem. We all depend on our stuff to work. It costs us money and time if it does not.
best wishes to you all in your struggles...
Alan