Thanks for the tips. I've tried out the VFFs twice now, with rather surprising results. I was expecting the feeling of wearing something between my toes to get on my nerves, because I tend to be sensitive about stuff like that. Instead I just felt very aware of where all my toes were, and when I put on regular (wide, comfy) shoes, my little toe felt uncomfortably squashed... Walking and running short distances with them I felt no strain on my calves at all, but I hadn't thought about how "wet" they are compared to regular shoes, just stepping on a patch of slightly damp forest soil I had water seeping everywhere. And my toes did get cold faster because of it. I'm wearing chopped off socks over my ankles to compensate a bit. While the mismatch between my own toes and the shoe toes I felt in the store just disappeared outside, no trouble at all.

Next step will be to try a real run with them, not just a hike+jog. Fun :-)