I had only minor problems with syncing over bt... The issue is that when you have activesync installed you also end up adding an activesync com port to the system. But with the MS stack it's not labeled and you just kind of have to guess.
First thing's first, you have to generate the relationship first via USB, this is a given but some folks might over look this. You might be able to do so over bt, but in my experience it works best to have the relationship already there before dicking with bt.
Next when you join your bj to your computer, you need to make sure that activesync is selected as one of the availible services you'd like to use. With the MS stack, it's going to be somewhat confusing. If you'd like to use more feature rich WIDCOMM anycom drivers please check out my article
here.
This way you'll be able to see which com port is the pre-assigned port and then you simply set activesync to listen on that com port. On your Blackjack, open activesync hit menu, press 6 or "Connect via bluetooth" and voila! I had it figure out in about 5 minutes and have had NO issues with it at all.
Granted all this could be because I'm using the WIDCOMM drivers prescribed in my article. The MS stack really blows.
BTW, my guide works well for xp users in addition to vista users(both 32bit and 64bit).
Good luck!