IMO, I concur with Leo about using the RO formula although chlorine WILL be harmful over time. Regular chlorine dissapates after about 24 hours of sitting in an open container with a wide mouth. ChlorAMINE does not- you need to determine which form of chlorination your municipality uses. If you're not satisfied with your water with the specs you mention, I'd probably recommend for YOU a deionization column system with a charcoal prefilter insted of an RO system. Since your water is already damn good, you'd just be polishing it off and DI columns which would be expensive to use in areas with hard water, should last a very long time for you. You can get single column, mixed bed DI systems that hook up to the sink at aquarium stores. They have a dye that changes color when it's time to replace and there is a layer of charcoal at the inlet to help remove chlorine, colors, and odors. If you want something bigger, maybe look at That Fish Place in Lancaster, PA or just Google deionization or deionization systems. Again, just my opinion. Hope it's useful info!
-Ernie