Exclamation [Q] Getting OTA from Google on custom ROM. What do I do?

I'm running Slimkat on my Nexus 7 2012. I just got a notification for 4.4.3 . I opened it and thought it was from the Slimkat guys. But it was from Google.

I also noticed that it was downloading through Google Play Services. I've Force Stopped the app for now.

What will happen if it gets installed. Will it break stuff?
I'm running the latest TWRP recovery.

Should I make a backup, or it will be fine?