Zedwrote a review of Black Diamond Quadrant Alpine Touring Boot - Men's on October 28, 2014
Familiarity: I've put it through the wringer
While there really is no standard for flex across the ski industry in my experience (25+ skiing, 10 racing, 7 race coach) these are as close to a stiff alpine feeling boot while still having the lightweight feel and maneuverability of a touring boot. You will want to play with the amount of forward lean that you set the boot to -- initially it is set up very upright which is great for walking/skinning etc but not forward enough for aggressive skiing. Just loosen the cuff and make 1 easy run making relaxed turns and then tighten the boots to that approximate forward lean (don't choose a powder day to do this). The overall fit of the last was in my opinion a bit wide; however, as with many boots this can be overcome with a custom liner. I would highly recommend that if you do get the Quadrant you consider purchasing Intuition custom liners through your local shop -- warmer and better fit which is key when you may spend 10+ hrs in the the boots (or sleep in them which I have done). Overall an excellent boot.