Hmm I guess what I read was wrong. It was on the internet so I'm not surprised lol. In any case, I still don't think 3 inches will hurt them at all. And most of the growers I've seen that use VS lights use both switches for veg. The more light the better. Use your best judgement. You can always lower it an inch a day and see how they respond. They will tell you it's too much light if they start to curl or yellow
I've been using both switches for veg and they are responding well they shoot out new leaves every day