After a few initial teething troubles, I’ve been happy with my Pure/KS i900Rs. Northwind is very happy with his Gravity Dropper (not available in 31.6 AFAIK, though) but occasionally admits that the i900R he has has been working well since Pure made the fixes they said they’d already made to it. 🙂
Another friend was pretty happy with his Joplin 4 until it failed on a wet ride. I was using one of my i900Rs on that ride and though its remote cable became a bit gritty it kept working and only needed the outer flushing out afterwards.
The people happiest with their uppy-downy seatposts were Reverb owners but I think that some problems started to show after the honeymoon period ended. I don’t know if they’ve been fixed.