Its kinda funny how similar the reef aquarium industry is to the grow industry. In the aquarium industry you cant find magnetic ballast any more. In the grow industry is still primaraly magnetic. I chose digi ballasts for there efficiency and fast start up, not to mention there dead silent. Im a long way from an expert on ballasts, but i have been using digi ballast for more then 5 years on my reef tanks, and i have had zero problems. I know everything has potential for issues, but digi ballast have been good to me. Well worth the extra expense IMO. I would never buy a ebay or off brand digi ballast, but the ones from reputable companies seem good. (ice cap, PFO, lumeteck, Sunlight Supply)