It's blowing my mind. I have a mixed stereo loop from Discrete Drums that I love, but can't use because the cymbals are too loud. Replaced the kick, snare, tom, and now they're loud enough to achieve the right balance with the cymbals.
And despite my skepticism, it really is zero latency. I guess that's how ARA fits into things. Unless there's some major glitch I haven't found yet with the Drum Replacer, I think it's going to be huge.