Hi avocado, thanks for reading my article, it was recently updated.
I'm surprised to hear that you have BBM5 running because as you might have read I could not get it working. Downgrading, I would suggest that you connect to you DM and then remove the BBM5, reboot the device and then add back the BBM that came with the 188.8.131.52. I did not have to worry about loosing my contacts, once I installed the 4.7 all my contacts came back. I would recommend however that you backup just in case anyway.
Also note that if you have a lot of contacts, you can actually type the first letter of the contact that you're looking for and the app will filter accordingly, likewise for googletalk and any other of the I'm clients. I would also recommend creating groups and place your contacts in them as well to reduce your scrolling.
Here's a link that might get you 4.7 as well. The download link is on the page http://bbhybrids.net/forum/downloads.php?do=file&id=42
Thanks, hope I answered your questions.