I just loaded 3jam and love it. I set a few conversations and had a few texts in each. Then I did a back up and tweaked my OS a bit a restored the back up. 3jam will successfully back up and restore!
Your good to go!
ALSO- Follow this thread to help figure out how we can get this to work better..
http://forums.crackberry.com/f134/of...fected-172365/
EDIT- I only had a few conversations and a few texts. Because while im still testing the trial, if it doesnt back up and restore correctly. It aint worth my $20 and theres no way I would use it as my primary sms app.