I purchased the Spike TC stone, and used it for several batches until I noticed that the tiny bubbles collect in the housing and tend to combine into large bubbles before entering the conical. This might not be a big deal, my beer fermented just fine. But it doesn't seem optimal. One of the stones with a long post that puts the stone fully into the conical might work better, but it wouIdn't work with a valve like the Spike one can.
So now it sits on the shelf, and I use a stone on the end of a long wand through a top port to reach near the bottom of my conical.
I've thought about inline oxygenating, or getting an adapter to put the Spike stone on the dump port, but the wand works fine for now.