I've been very happy with mine. In a recirculating system they make a ton of sense, root interaction increases hydrogen ions and the Torus removes them -- rebalancing the pH.
I ran a test last year where I went an entire flower run w/o changing my reservoir. I simply topped off with RO via a float and added nutrients as needed to keep the EC in check. I didn't have a single issue with pH going outside of range that entire run, I was floored. Obviously the nutrients were not balanced by the end of the run and I wouldn't recommend doing this, but it did showcase how long the Torus can keep a reservoir stable.
So far I've been away for up to 2 weeks at a time w/ the only issue being the reservoir running low. (I now have a smart plug I can remotely operate that will open a solenoid and allow the reservoir to refill via a float valve, I'd rather feed them straight water instead of having the reservoir run dry.)
I've also been logging my reservoir data every 5 minutes for the past 3 years via the Bluelab Guardian Connect, it's amazing how stable the graph looks. You can see the increase when a feeding cycle would run and then you'd see it creep back down until the next one. It made "riding the wave" almost brainless, my feedings through the day start at 5.8 and end at 6.2, then overnight it will drift back down to 5.8.