Tried the 11/12 3V last year for a day. I had skied for just 5 straight weeks at that point. I was able to handle them in a shorter length (can't remember exactly, but around 164ish) and had a lot of fun as they constantly wanted to be turning and on edge. But they were twitchy and difficult for me to control at speed.
Fast forward a year and I now have 15 weeks skiing and would not try them again. I like to go fast, GS style turns and mess around on the sides. Plus for work I need a flexible (not necessarily literally) ski that's adaptable to a wide range of conditions. The 3V was amazing on the crap, hard snow we had here last year, but on the sides was rubbish and too stiff.
I think the X-Kart is a great all rounder for intermediates/advanced, but probably too easy for experts (which I'm definitely not). It's forgiving of poor technique and lazy skiing, but will also go when you really push it. The Powerline core is the same across the 24 hours, X-Kart and Mustang. Except the Mustang has Carbon race frame and slightly different bindings. This year I've found the Mustang to be the fastest of the three but also the most work and slightly twitchy. I found this good though, as it forced me to focus on my technique. Any of them would probably be good for you, but at your weight, the Mustang is maybe a little much and the 24 hours doesn't necessarily have the flexibility you want.
When the Salomon rep was here last year he told us there were no changes planned for 13. Assuming that hasn't changed, it'll be cosmetic only across the range.
I think!! ;-)