I will say that while I was very excited to receive the Substratum Direct boots as part of my pre-Kilimanjaro care package from the good folks at Rocky S2V, they did not accompany on my journey to Africa. As I wore them prior to departure, I realized two things. First, they needed to be properly broken in before I could scale a mountain in them, and secondly they are incredibly warm, which would have been great on the summit push, but not so useful on the lower portions of Kili where you're hiking through muggy rainforests. For those reasons, I chose to leave them at home and carry a pair of boots that were more suitable for all of the climate zones on Kilimanjaro instead.
That said, it should be noted that these boots are actually fairly easy to break-in, I simply didn't have the time to do so before leaving for my climb. But upon return, I have been wearing them regularly, and it has taken very little time at all to get them completely broken in. They were already very comfortable straight out of the box, but the flexibility wasn't quite where I wanted it at first. But it didn't take long at all for the boots to loosen up, and feel more natural on my feet.
As with all of their gear, Rocky S2V has built the Substratum to perform incredibly well in the poorest conditions imaginable. They are completely waterproof, with the fabrics that make up the boot treated with Rocky's proprietary Hydro IQ which repels moisture incredibly well, while still allowing your feet to breathe nicely. They also use both PrimaLoft and Aerogels as insulation, which explains why they are so incredibly warm, even in very cold conditions.
Of course, it doesn't matter how warm and dry a boot keeps your feet if it doesn't provide good traction on the trail. The Substratum deliver in that department too with Vibram sole that sticks to just about any surface – wet or dry – and provides plenty of protection for the foot too. I've used these boots on dry and muddy trails, as well as on snow and ice, and have found that they provided excellent traction on all of those surfaces. Something that provides a nice piece of mind when heading out on more challenging excursions.
The Substratum gets high marks for durability as well. As with Rocky S2V's other products, the level of construction is incredibly impressive, and it feels like these boots were built to last a very long time. My pair looks practically brand new despite having a few miles on them. The designers of these boots picked high quality materials for every element of the Substratum, and while I've only had them a short time, it seems this is the kind of hiking boot that will last you for years.
Those high quality materials will definitely extend the life of the boots, but they also have added a bit of extra weight to the shoes as well. I don't have very many nits to pick with the Substratum, but they are on the heavier side when compared to the competition. If you're a backpacker or climber who counts every ounce, you may find that a lighter boot is more to your liking. But when you consider the level of durably, protection, and performance that the Substratum bring to the table, you may find that there is very little else that can actually compete with them in all categories.
As mentioned several times, these boots are quite warm. So much so that I'm not sure they'll be something that I could wear on the trail during the summer months. They are definitely well suited to cooler weather hikes, and will perform exceptionally well in the winter, but during the summer most people will probably find them to be uncomfortably warm. Keep that in mind when you consider what you're looking for out of a boot, and when and where you'll be using them.
Rocky S2V designs their gear to be used in extreme conditions, and as such they often build in features that are meant to help us survive in the backcountry, even when disaster strikes. With the Provision Jacket for example they include a handy little survival kit complete with a signal mirror, compass, and so on. Both the Jacket and the Provision Pants also incorporate the Recco rescue technology as well, making it easier for SAR teams to locate the wearer should they go missing. With the Substratum boot the mad scientists in the Rocky labs have incorporated two fire sparkers and two wet cubes in the insole, making it very easy to start a fire should you find yourself in a situation where that is necessary. This is a nice touch that helps set Rocky's gear apart from the competition, and while you may never need to use these survival items, it is nice to have them just in case.
The Substratum carry an MSRP of $299.99, which puts them into a more expensive price range than most people will probably want to spend on a boot. But then again, these boots aren't built for most people. They are made for the active outdoor adventure who demands high performance out of their equipment, and expects it to meet those demands in the harshest environments imaginable. This is a boot that is made for backpackers and mountaineers heading into remote areas where conditions can be a bit unpredictable, and they will serve those men and women very well. If you're in need of that kind of performance, than this is certainly the boot for you.
On a side note, Rocky S2V makes a lot of boots that are used by U.S. military personal stationed across the globe. Much of the design and technology that goes into those boots have also made their way into the Substratum as well. In fact, both of the Green Berets that accompanied me on my Kilimanjaro climb owned boots from Rocky, and had nothing but praise for their high quality and high level of performance. One of those soldiers even brought a pair along for the trip, and he wore them throughout. The Substratum take many of their cues from those same boots, and the Rocky legacy and quality is evident across their entire line of gear. I can't tell you how impressed I am with all of their products, and I will be recommending them highly for a long time to come.