Me: 6', 165 lbs, moderately advanced ability and age. Technical, like to turn, pay silly amounts of attention to my edge angles and pressures, CM etc. Do a bit of rec racing, mediocre.
Conditions: Killington, Vt., Day one: 2 degrees (yep, that's not a typo), 15-25 mph blowing snow. 1" fresh over hard chunked groomed (charitable term here), some manmade. Many runs closed due to lack of cover. This was some of the toughest conditions I've ever skied in, period. Day two: A balmy 12 degrees, 5-10 mph wind, drifts of manmade, 2" fresh, still very bouncy groomed but some comparatively smooth stretches.
The ski: Kastle MX70, 168 cm. Mounted with Tyrolia FF and plate at line.
I bought these last spring to replace my beloved but worn out 165 Head SS's, wanted something I could use to ski with the family in the NE, and still rip a bit on my own. But never managed to get them up and running. So this was their maiden voyage. This season and last's unchanged; typical Kastle wood core/rubber sheets/.5 titanal top and bottom. Same dimensions and construction as the RX12, but the bottom sheet of metal is .8 in the latter. I also own the MX88's, and in a while the FX94's. See a theme here?
Day One: I expected these to have the unique Kastle feel: precise, easy to initiate, and silky smooth, but with a lot of snowfeel. They did, and handled the ridiculous conditions mostly with aplomb. Better in light pow and crud than I expected, very lithe in bumps and tight double pitches, never felt uncertain or overmatched even on stupid-bad steep surfaces. Easy to weave down rough hard groomed, although I missed the cushy stability of my Heads - and a bit less grip on very cold hard ice than I hoped for, not real ice skates like Blizzard or Atomic carvers. But unclear whether that's the ski or the skier. (Did not tune them since Kastles are unusually a perfect 1/3 out of the wrapper, but may try that. OTOH, my second day this season, so...) In any case, grippier than my Heads for sure.
The MX70's ski very light, and the dual radius sidecut makes them effortless at initiation; they just dive into a turn with no fuss, regardless of conditions. Like an actual SL ski, they give you very precise feedback on everything you put in. That includes turn dynamics; the MX70's demand more attention than many rec carvers from the middle to the finish; you supply the shape, any shape, and the ski will take care of it. You don't, and well... these are marketed as intermediate skis by Kastle, but you can find yourself in real trouble if you get lazy. I'd call them an advanced to expert race carver for lighter finesse skiers. Also like a real SL, they don't especially like to run flat; at speed the tips keep searching for something to do. The 176's - based on Dawg's review - are probably more the ticket for higher speed or lower edge angle work. But if you're over 180, have a hunch you'd be happier on the 12's.
By comparison, my Heads were heavier and more secure feeling on the same slopes last year, took a little more decisive initiation, then had a more "locked in" feeling once the turn began. Not as happy changing shape, pressure, or style once into things, not as much information from the edges about how things were going. Less demanding, all in all. Another point of comparison, same slopes, would be my old Fischer RX8's: They had better grip, more kick from the tail, not as stabile or smooth, not as effortless to initiate, equally adept at shifting shape, but less precise in doing so.
Day Two: Conditions were better, snow surfaces a little softer, and I let these out a bit. They didn't like piled up chop along the sides at speed; fronts got nervous. I attribute some of this to the cutaway tip; not much mass there to fight off impact. OTOH, they ran nicely on anything-but-smooth hardpack at up to about 40 mph, as long as I stayed on edge and kept my form together. Not what I'd call relaxing, but not sketchy either. To extend Phil's car metaphors to motorcycles, these are like a small Ducati; perfectly capable at speed, but part of the rush is in staying focused and using the feedback. If you want to cruise at mach 2, get a Hayabusa.
However, speed is not why I bought these. Later in the day, legs weary, I did a few runs with my two boys after their ski classes were over. The MX70's were perfect. If I had been on my Heads, I would have been fighting the ski's heft and desire to pick up speed. On these, I could carve nice slow little railroads on green runs, talk with the boys as we skied, goof around with 360 spins (tails are square but raised just enough) and know that the same sticks had been fine ripping steep icy blacks across the valley. Nice...