I was/am against the idea of the Dialyseas device. We have a water change system in place and use other cheaper methods of reducing excess nutrients.
Having to rely on the accuracy of a salinity probe is a position neither Peter nor myself want to get into. Furthermore, salinity shifts and ionic imbalances is a chemistry lesson/exercise we want to avoid.
Ken Feldman did a thorough review. He bought one for water changes, not water quality, due to limitations with the landlord.
http://reefkeeping.com/issues/2006-04/pr/index.php
I agree, in my experience electrical conductivity salinity probes are useful to show trends but often inaccurate with spot readings, I have used them for many years and commonly see fluctuations of 10% without any appreciable salinity change when measured with a refractometer