How likely am I to lose my data if I flash Xposed Framework for Lollipop 5.0.2?

I have a Moto G 2nd Gen 4G (XT1072), which I rooted. I want to install Xposed framework for Lollipop, but I want to know that if I flash it from a custom recovery, will I lose any of my contacts, app data or game data? Also how likely is it to brick my phone or give me boot loops? Does a Nandroid backup, backup everything - including partitions, app data, etc?

Sorry for all the questions, I am new to this.

Thanks. :)