I had not looked around on this subject for a while. There is no question that sulfates in batteries is bad, so in theory these things should help, but to what degree versus cost is issue for me. A neighbor installed one of these and came away with very little data. In the end his perception was it did not help, but that is strictly opinion. To me, if someone tries this they must collect some data to measure results. I have yet to find that anywhere. $140 is not short money in relation to $625 batteries depending on results.
Here is a link for your reading pleasure:
http://leadacidbatterydesulfation.yuku.com/directory
A thread where some data was collected here:
http://www.buggiesgonewild.com/elect...t-fiction.html
If someone goes this way it would be great to document details,e.g., battery voltages at various states of discharge, etc and share.