I think the coombas and the obseth are pretty close in flex, the coomba might have a slightly stiffer tail, but both are WAY softer then the mantra.you prob got tip dive because the mantras tips don't float up because of their stiffness or they could be to short for you, The rocker in the obseth will give you great powder performance, but i think the gotama would be better on groomers, If you have no need for twins i would try and demo the coombas, they are the lightest of the group and seam like they would be a really fun ski. The reason i say this is because they will give you a more traditional feeling ski like your mantras vs the obseth and goat.I would go 179, k2's run long so they will be around 183 to 184, the 189 would be good if you were skiing big open mountain all the time.adding--- You sound like you need the new Black Diamond Megawatt. It matches your exact description for what you want in a ski, (except for bumps probably). But these skis are not twin tipped, and they only have a rocker on the tips. They are plenty wide for the soft stuff, and EVERYONE LOVES THEM!!! What more could you ask for in a ski. You should really take a look at these things! They even come in a 178 for you.http://www.backcountry.com/store/BLD1152/Black-Diamond-Megawatt-Ski-08-09-Model.html