Well if you'll take my experience versus this as evidence I'll say I never had bad experiences with my coil bulbs and used 2 different ones over 2 years, both mounted horizontal.I read a piece about the type of bulb you have there a while back and I never could find it again, but it said that if you mount that light horizontally it doesn't cause the eye burning problem. Seems the harmful rays are concentrated out the end of that bulb, and horizontally they are dispersed rather than concentrated downward. I've never tested it, my tortoises' eyes are too precious.
I didn't actually change to my MVB mostly because of the risks like these stories, I did because these cases made me think how much I hate working under fluorescents and they hurt my head, so why force Nank to live under one.
But in the small cases I agree with that theory, Nanks acted no different with either light.