I’ve discussed the conundrum that is nordic backcountry ski boots before, and no doubt will again. I’ll reprise my wish list for such a boot at the end, but given that it does not yet exist, comparing these two will have to suffice. Refer to my thoughts and pictures of the Fischer boot in this post for comparison.
A good nordic BC boot should stride very well, have enough support to (survival) turn and edge 70mm waisted skis in most all conditions, and be able to hike for miles in varied terrain with no blisters and modest efficiency. It should be warm, waterproof, absorb minimal water when soaked, and dry fast. It should also be light.
The balance between hiking/striding and turning/stopping will be a continually negotiated problem for as long as skiing is skiing. There will be better or worse solutions for various skis and skiers, but few inherently wrong answers. The rest of the qualifications listed above can already be answered by existing technology, and thus both boots failures to fit these criteria is merely a subject for excoriation. I realize most users are probably taking these on day trips, but that is still not a good excuse for makers to not have their shit in order.
The 675s were 2 lb 7 oz a foot in size 45. The X11s are 2 lb 12 oz a foot in size 45, which is totally ridiculous. Boots in this category, especially those with the less beefy performance of the X11s, should be sub 2 lb a foot. Putting fit issues aside (read about my irreconcilable differences with the 675s here), the 675s are a substantially beefier boot. The sole is stiffer and much more resistant to twisting flex, and the upper is both taller and more supportive. Compare the photo at left, of the X11, with this photo of the the 675. The former is soft and easy flexing all the way down to the stitching below the R, allowing the plastic cuff to pivot and the whole thing to move freely. The 675 has fiberglassish reinforcement in the upper heel (white material), and thick pleather all around the ankle. The cuff of the 675 is less substantial than that on the X11, and it lacks the ratcheting buckles, but the stiffness in the soft material of the 675 means it strides worse and controls skis much better than the X11.
Different users will prefer one over the other. I like the enhanced striding on the X11, though I didn’t find the sole stiffness of the 675 problematic for hiking. I’d prefer the X11 was more like the 675 in this respect. Softer uppers can be compensated for, to a certain extent, by strong legs, but only if the sole is decently stiff. Adding to my displeasure, most of the weight in the X11 seems to live in the sole, without adding the benefit that it should. Boo.
The ratcheting upper buckle on the X11 is no better than the velcro strap on the 675, and I’d probably prefer the latter for the sake of simplicity and weight savings. Neither boot has enough structure that high to make a ratcheting buckle worth much. The lower buckle on the X11, however, is eminently worth a ratcheting buckle, and this feature is a highlight of the boot. In my book laces don’t provide enough resistance against foot movement when schteming for all you’re worth down a narrow trail, or straining to turn skinny skis in deep snow. The lower buckle on the X11 does a fantastic job of keeping the foot locked in under duress.
The X11 seems about as warm as the 675 but has ‘thermo-moldable’ material inside which is much less squishy than that in the 675. This stuff is supposed to mold under body heat, a claim I very much doubt and thus far see no evidence of, but it’s perfectly comfy and absorbs a lot less water than that in the 675. Both boots are mostly waterproof. I sealed all the lower seams of the X11s once I decided to keep them, but haven’t put this to a rigorous test yet.
Fit of the X11 is fairly middle of the road. My heel stays put well enough, and unlike in the 675s my forefeet have enough room, and there is no pinching or other nonsense. The inner bootie and lacing is secure and adapts to a wide range of feet. The vibram sole of each boot is, as far as memory tells me, identical and quite functional for hiking on rocks and dirt. The X11 is far from a perfect boot, but because it fits and hits a decent performance balance it will be my main nordic boot until something better comes along. It matches well with my Outbound Crowns (70/60/65), though due to the softer sole I’d hesitate to use it with anything much wider. I would not use it with my Guides (109/78/85) or Hoks (120/109/120) save in close to ideal powder. The later would be manageable due to the short length and easy turning design. The 675s, being substantially beefier, could ski the Guides in corn, though not on resort hardpack.
The ideal nordic boot with be a synthetic, primarily soft fabric double boot with a thermo liner from a company like Intuition. The outer would match a sole like that of the 675 with a cuff like the X11. The taller liner would provide a bit more support while still allowing good flex. Most importantly, the design would be warmer and much drier under real backcountry conditions. Especially in the spring, keeping boots totally dry is not realistic. Designs ought to start addressing this.