I'm 6'4 200 and just tried out my new T Rice 161.5 this past Sunday at Loon Mountain in NH.
There's no snow around so of course i knew the conditions would suck, but i'm going to Utah soon and wanted to work the kinks out of the new setup. It was pretty damn icy, crunchy, and hard packed. This was a great test for magnatraction and i can now say that i'm a believer. It clawed like a champ and really dug into the ice. There is no way in hell i would have stayed up in these conditions on my old board. With the magnatraction, i would still skid and slid, but it would do so in a controlled and predictable manner so that i could control it. No sudden washouts when transitioning to some snow/grip onto a sheet of ice. There was one run that was totally iced over at the end of the day and people were dropping like flies all around. Skidding down very slowly, etc. I had to be slow and very careful, but i was able to navigate my way down without drama.
The board does hold a carve very nicely, and i agree with the OP that it doesn't feel THAT different from my old traditional cambered board. My old board was a Sierra Crew (which i think is a 2008 Burton Custom relabeled) and this felt faster, more damp, and carved just as well. Add in the whole-new-ball-game of grip with magnatraction and i'm a really happy camper.
Now if i could just get some snow to really test it out.