Interesting, I found your note on photo.net regarding the D250 and it gumming up from hard water -- but how you're otherwise happy with it. I guess it's a good sign you still like it a year later! Paul Butzi also seems to have only good things to say about it. I may actually spring for one of these... While expensive it does seem like an excellent investment. He mentions a low-flow option, I bet I will need this for the ATL-1.
Pardon a dumb question, but what's CLR? Chlorine?
I was planning on putting a filter after it, but I guess putting two before will keep sediment out of the valves. Good idea. I was planning on two feed valves on the lines before it so I can take it off if necessary (I just assumed the plumber would do this automatically); will I also need vacuum breakers to remove the mixer?