It was been quite I while now since I did the tests so Larian could have changed things...but I couldn't find any real use for that ring in the EA up to and including the Druid patch(that is the last I played).
I did a run where I used a flying pet to make its way to the myconid village via flying down from the Blighted village and through the spider's lair to the UD. Once the pet discovered the myconid warp stone I warped me and SH from the beach warp stone where they had been waiting, fresh off the crashed ship. I did Omeluum's quests and got the ring then warped back to the beach and started the surface content all with the ring equipped to look for affects.
You can still use the tadpole dialogue options.
Dialogue option use still triggers dreams.
Enough dialogue option use will still result in everyone getting the tadpole powers.
I believe companions can still use the powers if you are wearing the ring. It only stops you.
I did a longer post on it all previously but don't have a link off hand. I do remember seeing mention of a potential datamined negative effect from tadpole growth that is suppose to happen at some point that the ring may or may not prevent.
