I agree. Also i have noticed no difference between conversion bulbs and dual ballasts in my experience. Hell of a lot cheaper too.When something craps out in the dual ballast, you're out 2 lights in a sense. Conversion bulbs are cheap, replaceable, and don't complicate a reliable process.
Your best bet is to buy one of each.Dual-Ballasted (the ballasts that can house a MH and HPS bulb) VS. A conversion bulb? Pros & Cons of each?