Sync Services eliminated from Mavericks - can no longer sync contacts

Question

I clearly made a big error updating to Mavericks. I only discovered after the installation that Mavericks no longer supports Sync Services, which was critical to my ability to sync my personal contacts and calendars to all of my devices. In the absence of restoring my computer back to Mountain Lion, I am wondering whether there is anything I can do, but I fear the incompatibilities are too great to surmount.
My work email, contacts, and calendar are on a 2003 Microsoft Exchange server, and I have no power to change that. That apparently means that the only Mac email client I can use to sync my work contacts and calendar is Microsoft Entourage 2008. (The email is less of a problem, as I believe I could access it through IMAP.) I had also been using Entourage for many years for my personal email, contacts, and calendar, so it has been nice having everything centralized in one program. To sync my personal contacts and calendar, I was using Sync Services to sync everything first with Apple's Address Book and iCal/Calendar, and then those were synced with my online Google account to serve the rest of my devices.
I had everything set up, as described above, to conveniently sync everything in all directions. Then came Mavericks and the unexpected loss of Sync Services. Now, Entourage 2008 is completely isolated from the outside world with regard to contacts and calendar events, and I believe the same would be true of the newer Outlook 2011. (I never even bothered to upgrade to Outlook 2011, because it apparently is not compatible with 2003 Exchange Server, so it would not have functioned with my work contacts and calendar.) Apple Mail is also apparently not compatible with 2003 Exchange Server. I tried DAVMail to serve as an intermediary to no avail.
Then, I thought, well, perhaps I could continue to use Entourage 2008 for work email, contacts, and calendar, and switch to Apple Mail, Address Book, and Calendar for my personal email, contacts, and calendar. That is not particularly convenient, but perhaps it would not be too bad. However, I cannot figure out how to transfer my hundreds of calendar events from Entourage 2008 to Apple Calendar. There is an "Import from Entourage" function in the Calendar program, but nothing ever gets imported. It will launch Entourage, if Entourage is not already running, and it will crash Entourage sometimes, but nothing ever gets imported.
I can also export my calendar events from Entourage in RGE format (some sort of archive format), and I could probably also get them into Outlook 2011 and then export them in OLM format. However, Calendar cannot handle either of those either. I am also not particularly impressed with the functionality of Calendar relative to Entourage/Outlook's calendar system.
So, now I am wondering whether my best option is to restore my computer to Mountain Lion and hope that my work will eventually change to a 2007 or newer version of Exchange Server. It seems that there are a lot more syncing options on the Windows side of things, as well, so I am thinking my next computer is going to be Windows, and I am due for a new one soon.

Answer 1

I restored to 10.8.5 using Time Machine. However, Time Machine immediately seemed to get confused and tried backing up my entire entire hard drive, even though I had just restored it and nothing had changed. This process went on for like six hours, and I was afraid to interrupt it. In the end, it failed, because the backup drive was too full. But it kept trying unsuccessfully to backup the whole thing, and I could not figure out a way to make it stop! Eventually, I had to reformat the backup drive and start over with a new backup, which took another eight hours.
I am going to buy a new computer in the next few months, because my current Mac is over five years old, but I will likely switch to Windows after 20 years of using a Mac at home. It saddens me a bit, and I know that my sync problem with Entourage/Outlook is probably mostly the fault of Microsoft. However, I must have compatibility with my system at work, and the simple fact is that is not possible on the Mac without jumping through hoops.
In addition, Apple presented Mavericks as a free upgrade in the App Store and promoted all of its alleged new features, but they did not list the things that had been removed (including the Sync Services functionality on which I depended). Given the widespread usage of Office for Mac, I would think it might have been good for them to reveal that broken functionality more prominently. Then, of course, there was the fiasco of trying to restore things back with Time Machine.
Sigh....