backup - adb restore across different devices, android versions

Once upon a time, I ran this on an Android 4.3.0 Nexus 7 2012 running ParanoidAndroid:

adb backup -all -nosystem -apk -shared \

  -f backup-all-nosystem-apk-shared-201309132331 

Now I would love to restore at least one of those apps on my Android 4.3.1 Nexus 7 2013 running vanilla. (I haven't installed it.) I've preemptively ran:

adb backup -f backup-all-system-apk-noshared-20131027111818 -apk -noshared -all -system

and now I wonder: what could possibly go wrong if I restored the original backup? Would re-applying the backup I've just made on top of it get me to a... working system? Do I want to take additional safety measures?