to some degree, the digital ones can not do this due to the frequency. An HPS digital ballast needs to have a conversion bulb in it. the main arch to light the bulb will destroy a typical MH.
Not true. Digital ballasts are designed to fire either bulb. Now some HPS bulb makers will not warranty their bulbs when used in electronic ballasts. Hortilux being one of them. But...Lumateks new dimmable ballasts with soft start technology will fire them just fine with no issues.
But you are right the magnetic ballasts can run wither, still gives it a little less life time but its not as aggressive on the bulb as the digital ones are.
I prefer magnetic anyway, way easier to repair.