I bought a RD-106 from the same company...There were some ammenities I wanted for my unit that made it easier just to buy a new one. I liked the two tap thing. It has one that runs from the DI for my reef and a tap for pure drinking water, that was the main reason. Also, I'm now setting it up under my sink instead, which can be done with the RD-100, but I like spending money. No problems with the one I've been using, even with the filters being over 1.5 yrs, after a minute or two I am still getting 0PPM output. To tell you the truth, I'm really not worried about selling it, which is why I have not created a separate post. I could always keep it as a backup if noone wanted it.