The 179cm ObSETHed will ski a whole lot different than your Mantra's because of the added width and the mini rocker (reverse camber). Also, on your sizing, K2 skis in general are measured different than the rest of the industry. A 179 ObSETHed is bigger than a different brand 179. So the 179 ObSETHed and the 182 Czar might be very similar in length. I would really recommend either the ObSETHed or the Czar because of the rockered profile. You will like the rocker in softer snow, and the Rossi S6 is just a regular cambered ski. So unless you want to give up the rocker, stick with the ObSETHed or Czar.As for your experience on the 189's, if you liked the way they skied, despite the length and the heavy feeling, the 179 should give you the same feel, but they will be more nimble, and they will feel lighter. Any ski that is too big (a 189 in your case) is going to feel heavy and it will take more energy out of you to get them to cooperate. In general, the same skis will feel very similar in each of their different sizes, but the ski in your size will feel easier to work with. So like I was saying before, the 179 is going to feel good. In my opinion, you should stick with ObSETHed's because they are so awesome. But I can't really compare against the Czar, because I've never skied it. Keep the questions rolling if you need any more help!Troy,I say go with the Czar for sure. Similar shape with the rocker just in the tip which is a great idea, but the foam core makes it a much lighter ski. I'm debating between the two right now myself. I loved the way the Obsetheds rip, but will by touring with them so leaning towards the Czars.I agree, if you are going for a rockered ski the czar is the better of the two, and if you truly want the obseth at least demo the line bacon first its less hookey in powder and floats better without the rocker plus it skis groomers way better, a very similar flex but much funneir ski.