Never used it, but it looks nice. I initially thought it was like the BRS Dual Reactor with single flow through, but each one is independent with separate flow control. I would buy it.
The dual flow controls look nice and Spectrapure has a good reputation. I have one of their RODI units and they've been great about helping me out when I need it. I know that doesn't answer your question about first-hand-experience but I really like Spectrapure.