how do they hold up with a ruck?

They have, thus far, been outstanding while carrying a heavy pack. They break in fairly quickly (so don't buy too big a size, they will stretch a bit, especially if they get wet) and are very comfortable. As far as durability, I think they're solid. That having been said, you'll want to give yourself (if you haven't yet) plenty of time to get used to a flat/barefoot type shoe. If you aren't used to it, I wouldn't load a full-size ruck and try to knock out 5 miles. That will be very tough on your feet and lower legs. If you're already a minimalist shoe person, then they are excellent and are holding up well in everything Colorado has to offer.

Would they work for motorcycling?

Do your research. From what I have read these boots do not come close to what a proper motorcycle boot should be, if you really want to be safe.

Does it fit well? i'm asking this because i'm an 11.5 regular and i bought thes other tactical research boots and they were to big. should i get 11s?

They fit like normal. I'm a 10, bought a 10, and they fit perfect. However, they are rough. They make a lot of noise. I ended up returning them because of their lack of comfort. I went with Nike.