After I sent in my first results, I received an email from PocketMac informing me that the Beta was intended to be closed/limited, and that whomever posted the .dmg file initially, did so without permission. The file will remain offline until the closed Beta is complete. There may be another Open Beta later, or it may go straight to production, the email did not specify.
I tested a full 2-way sync with my 8700 and encountered no issues with duplicate notes (as in 3.x), no dropped phone numbers, no addresses in wrong place (home in work section), no duped calendars or incorrect repeat entries.
In short, 4.x seems to be what we've been waiting for. Well, for those that can get it to work at any rate
For all you having issues, have you used Onyx or ****tail recently? I use Onyx at least once a month to keep OS X in good shape. Might want to consider it if you don't.