I've been using a pair of the Voyageurs for hiking for about a year. Most of the use has been day hiking in the Columbia Gorge, but I did take them for a couple of months of backpacking around the Pacific Northwest, with the longest trip being 7 days (60-something miles), carrying loads up to 30-45 lbs. I would not recommend them for backpacking as they aren't stiff enough and lack the underfoot support to carry heavier loads. Of course, they're not supposed to be backpacking boots, so for dayhikes I think they're pretty decent shoes, though they have some problems. The first one is the lacing system with the leather bands. The leather uppers in my shoes stretched out (in width) after a few weeks and the leather bands make it difficult to fully tighten the laces without creating pressure points, especially at the top of the tongue where there's a gusset. Likewise, it's hard to get the heel tightened in fully (the heel webbing strap is purely cosmetic and does not help in this regard), so I always have a little bit of heel rub, which isn't really causing blisters but has prematurely worn down the lining of the inside of the heel of the shoe.
The second problem is the sole. For some reason Keen molded the sole with colored rubber caps over the tread, and on one of my shoes the caps started falling off and other glued parts of the sole began to peel away. (See photo - note that the bottom shoe is missing some of the gray rubber bits - more are missing now, though the other shoe is totally fine.) I've continued wearing them and they haven't completely delaminated or otherwise catastrophically failed, but it's not something you expect your new shoes to do. I contacted Keen and to their credit they shipped me a replacement pair for free (allowing me to keep the old pair, which I am trying to wear out completely before starting to use the replacements) - their warranty service was very good. But it's inexplicable why they would even design the sole this way in the first place - if it were a one-piece molded sole (like Vibram usually makes), there would be no rubber caps to fall off. Furthermore, the traction of the sole was usually mediocre, and especially poor on gravely trails. (The exception was crossing water-covered granite slabs in the rain with a full pack, where I had full traction and never slipped, while my friend in Oboz shoes, who always had better traction on the gravely trails, fell a number of times.) The rubber in the sole is also somewhat soft and the tread pattern a little less aggressive than it could be. I think the shoes would benefit from a very dense, aggressive, one-piece molded sole like the one on the Lowa Jannu.
Otherwise, though, the shoes are quite comfortable, even on long dayhikes. (The longest I've taken them on was nearly 18 miles.) Breathability is good, though water leaks in the mesh side panels if you're not careful about stepping around puddles. The durability of the upper seems fine and the leather is showing low wear even after a full year of use. The forefoot part of the midsole is actually somewhat soft and flexible, so the shoes are somewhat nimble at the expense of being able to feel pointy rocks underfoot. The forefoot is quite wide and I would say these shoes best fit a medium to wide foot, though this is nice for longer hikes because there's room in the toebox as your feet swell.Overall, I would say these are decent shoes: very comfortable, good for long dayhikes on well maintained trails, but they could use some design overhaul of the lacing system and especially the sole.