Thank you Justin and Trithor.
Most of my plants are in moss, it is my preferred medium since it is easiest for me to tell when it is dry.
I usually kill everything in bark.
I moved some mature phals in large pots to bark to try and they seem to be ok, but they had very good root systems when I moved them, so maybe eventually I will kill them too.
My adult paphs are in bark mix, but I do rot a lot of roots in it, when I repot I see their root system getting smaller and smaller. I keep them in bark because that's how I bought them and not sure if I can move them to moss safely.
I am hoping that these new seedlings will get used to moss and will continue to grow in moss when mature.
I do change moss often, so it doesn't have chance to pack up too much.