Ill disagree,
You may get away with low pressure in sand and mud, but when riding thru rocks at speed I think at least 15 lbs is needed.
At the Montrose Enduro here in Colo. for example, a ton of people were getting front flats and I suspect it was from too low of pressure. Were not talking about a few rocks on the trail, were talking there might be a little dirt around some of the rocks. I would rather feel more confident of not getting a flat than a little better responce from the front end. I run moose hvy duty tubes with slime, never had one go flat yet.