So I read this as you haven't had a chance to ski your new Line's in powder yet and are looking for opinions on how they will do. I am 6'4", 245lbs, expert. Short answer: they will do fine. Longer answer: if you want to float on top of the snow you need a lot wider ski, but they will give some float so you won't sink to the bottom and they will be fun to ski in light to medium powder. Very deep (+16") heavy wet stuff maybe a little difficult at that width.
I have a 101mm Ski Logik Chariot that I use in soft snow (no rocker, very wide tips and tails). In 3 feet of light powder I sank about 2 feet. It was really fun and easy to control. I had that floating on a cloud feeling as long as I had some speed, when I stopped I hit bottom. The Chariots float me some in all snow, they are really fun in spring conditions. The tips do dive in powder, so I have to keep off my tongues. Your Lines should do somewhat better, as they have more rocker and you are lighter than me.
If you want to float on top, I predict you will need a 120mm + width. I use a 143mm width for a powder ski, and it floats me on top. I know from another Epic member exactly my size that 125mm will not float him on top, close but they sink some. Rocker and ski design will make a difference in how much float you will get.
Bottom line is your Line's will ski really well in any depth of powder, but you will sink down into it some. A lot of skiers prefer this feeling to being right on the surface. I haven't skied enough powder recently to have an opinion. I like any powder on any ski, but width does make it easier and less work.
Alright thank you