Hard to say as LED's vary a lot in quality and intensity. Leaf curl can be caused by many factors, so make sure all other factors are correct before assuming the LED is the problem. I've also had very good success combining LED with T5HO as well. Seems to work better then either alone. Hopefully your LED does have sufficient power. Anything under 120W or so is usually insufficient. Those 14 and 28W units are generally useless and just a gimmick.

Well it's a UFO shape but it's a 100w from Gotham Hydroponics. The leafs aren't drying out...just really curly. Pics below.

Sometimes just adding a light fan helps keep the heat from the light off the leaves... Just one of many possible problems/solutions. Plants look great though. GL.