I really agree with the "experience lets you carry less" comment. To my earlier blaze comments about thru-hikers carrying less, I feel compelled to add (or detract :)) that a flurry of discussion is happening now on the PCT discussion list about a thru-hiker that went into the Sierras a few days ago with a relatively light load of gear and ended up hitting 911 on their SPOT due to becoming somewhat hypothermic.

It can definitely "creep up on you quickly" if those conflicting terms make any sense to you. What would be an inadequate and unsafe set of clothing and gear for one person could be fine for another who has a higher combined total of relevant experience, knowledge, creativity, and wisdom (primarily common sense).