Slim,

I don't have either, but I have done a lot of research. I may be wrong, but I believe a RO and a DI filter are supposed to do the same thing; provide PURE water. Some set ups include both a Reverse Osmosis filter with a Deionizer. This set up is needed in some locations to add a longer life span to your DI tank. (locations where there is a high TDS count) With a RO system, you need to replace cartrides. With a DI, the resin is "regenerated" using a salt and acid flush. I have found that several of the main manufactors of these systems have been very helpful with answering any questions. Hope this helps.

Micah Kommers
We Wash Windows www.we-wash-windows.com
South Carolina

P.S. The only reason why I don't own a system is because most of my work is ground work. If I did residential, or a lot of pole work, I would def. own one.