I've been using this method since this post came up. The only difference is like Scarface listed above which is, I mix my water over the course of a few days in a separate container, drain half of the amount of my water change using this method and the other half is siphoned, cleaning ditritus that has settled into my sump. Then I add in the mixed batch of saltwater.
An honest assessment on how effective it is would be difficult because you never know if it is something else you did which caused the changes. I change 30 gallons per month of a 230 gallon water volume. So roughly only 15 gallons a month is removed this way. No change in PO4 or nitrate, which are low in my tank anyway and I already have systems in place to keep them that way. I would say that my water is clearer, but not sure if it could be attributed to that.
I like changing my water this way. I use the downdraft skimmer to do this, not my euroreef, since, for me it is easier to adjust the downdraft and it is set up with a drain on the collection cup.