Keep your "master" data in one place.
I think you should keep your appointments action reminders in one place. I lived with split systems for a while and it hampered me, especially at the weekly review. You can do it, but it makes GTD more difficult (IMO).
Like Stephen Covey suggests, keep one master calendar. If you can't synch your work calendars directly to it, you have to copy the data into it manually. The same thing applies to action list reminders.
Since you're using Outlook in both places, you might be able to export bits of your calendar to CSV files, e-mail the CSV files home, and import them there. That will cut down manual re-entry. If you can't, you'll have to manually update your lists either on your BB or the computer to which it syncs.
I know nobody wants to do double-duty entering things, but having it all in one place requires that sort of thing. Shared Outlook calendars existed before PDAs that could sync to them. What did people do? They took their mid-tech planners and copied the appointments by hand.
This is a personal choice thing and not a black/white rule with GTD.
If you do decide to blend them, it's not so much that they relate to each other, it's more about having a comprehensive system that allows you to toggle between whatever you choose to focus on, easily.
For what it's worth, I have:
Computer - Personal
Projects - Work
Projects - Personal
Someday - Work
All other lists are blended personal/professional, which works fine for me. All kept in the same system though of Lotus Notes.