Electrostatic oil cleaners are excellent contamination control devices for some applications. You seem to have a good grasp of the basics. As one post pointed out, they excel in areas where degradation mechanisms are at play causing deposits.
Although they do not work well in the presence of water, you will have much more urgent concerns if you have a high water content in your oil. Electrostatic oil cleaners continue to work well again once your water problem is under control.
But, no contamination control device will take the place of oil analysis and conditioned-based oil changes.
Finally, I encourage you to read some of Dr. Sasaki's papers and research on electrostatic oil cleaning for additional information. He has done exhaustive research on the subject and his findings have been widely published.