Yes, with the
6.3 update, I also forgot to re-enable DroidWall and it updated me, but so far, knock wood, with that file that I removed I have not received the 6.3.1 update.
How do you "put back /system/xbin/su" in case I have to do that....do you need Linux installed on your PC? I'm using Win 7, 32 bit and I had to re-root by going through the FireFireFire steps again with
6.3.
But like I say so far so good with the removal of that one file - no update to 6.3.1.
I have to reiterate that it is not really necessary to be rooted at all; you can use Go Launcher EX and Rotating Wallpaper app and sideload nearly all apps without rooting. There's a Live Wallpaper you can use to rotate wallpaper also.
I just have time on my hands and like to fool around with my devices.