Yeah. I'm not sure. I have 3 giant hairy mushrooms and "1 and a half" ricordeas. (I say that because it just dropped a baby a few weeks ago and it's not much more than just a mouth. LOL!) I would think the giants would over run the ricordea.Great question. If you search for coral v coral thread here you will see almost everytime the mushroom wins regardless of species and coral.
This is something I am curious about as well as I'm about to convert a couple racks to rocks in a couple of my tables to allow my shrooms to move free.
To date I have housed similar species together within reasonable distance. But I could still move them around if they encroached one another on the racks without an issue.
This may be impossible in a tank without proper planning and ability and enough space to keep moving them when needed.