That's what I do to, because then I would need to pull and push the files. I was talking about in general making the /system a RW; for other needs.
I use root explorer too, and that automatic backup is a great feature. Gives you some peace-at-mind when doing this.
You have to be careful with the backup feature though. I made two changes. the first one was the camera button change. It made a backup. Then I made another change for the volume buttons. It made a backup of the file with the camera change. So it overwrites the very first original backup. Its probably best to just backup the file the first time and keep it in a separate folder or something so it doesnt get overwritten.