Actually, I tasted the Sidra de Nava at a release party this summer, and remember disliking its overwhelming acidity. I found it startlingly sour, tasting of lemon, sour grapefruit, and tart apple, and had trouble finishing even a few ounces of it. This time, though, I liked it. I don't know whether the cider is less intense in a bottle than on tap, or if I just reacted to it differently this time, but while it's still intensely tart, it seemed refreshing and crisp rather than overwhelming. Sidra de Nava smells like a Granny Smith apple but with a little yeast; I got the same lemon/tart apple flavor as before, a little like a sauvignon blanc. As the cider warmed up the fermented flavors became more pronounced, reminiscent of kombucha, with vinegary, saline, funky notes. That may not sound particularly pleasant, and I still wouldn't want to drink this in large quantities, but there is something uniquely appealing about it, and I'm sure it would pair well with food (especially fatty food like cheese).
The Percheron is a much less challenging cider, mellower and sweeter than the Sidra de Nava. It smells like baked apple and chamomile and has a full, round, earthy flavor that reminded me a lot of roasted dandelion root tea (which, if you haven't had it, tastes nutty and roasty). There's a sort of barnyard quality to it, with notes of hay, but the earthiness is balanced out by the finish, a sweet tartness at the back of the mouth that's almost tingly. So far the Mitten has been my favorite Virtue release, but I'd like to taste it side-by-side with the Percheron. I could well have a new favorite (not that it matters which is my favorite, really, since they're both excellent ciders).