This place says ionic is better:
http://www.health2us.com/
From what I can tell, a low voltage direct current(LVDC) makes ionic silver where a MHVAC(medium high voltage alternating current) makes a combination and the HVAC makes the hightest % of particulate vs ionic.
CS Pro sells a MHVAC system.
http://www.csprosystems.com
I could not find their HVAC system from their home page, but another link gave the link below.
Tell me what you decide to choose. I would like a big enough one to use to spray trees for fungus and use in a swimming pool, but am in the same boat you are with which kind of silver is best.