Adding a backing to the all coticule one may be a good idea. I doesn't seem necessary at the moment but I will regret it later if it happens to crack. I would probably add a regular natural stone not used for honing. I already have BBWs and even with another hone I would have to handle it with care to not scratch the bottom of whichever side is up.

I am careful with all my hones but I already managed to scratch the BBW side of the natural combo within a day after lapping. Fortunately it only took about 20s on 800 grit sandpaper to remove it.