I practise martial arts in tai chi shoes when we are studying in the smaller dojo with the tap dance floor, because I broke my left foot as a kid, and three or four toes on either side. It starts to hurt like hell if I don't wear the shoes, and the ones Steve mentioned are just right for me, as they are light, and have good arch support - particularly good for my left foot.
When I am training in the larger dojo with the padded floor, and when I train on grass I practise in the bare feet, because I do think that you learn more subtlety of movement by practising unshod. I also believe in chi, though it is hard to explain what I mean by it. At the risk of sounding clinically insane I will only say that it is like a mild current that flows through you. I don't pretend to know what it is, and I only feel it when practising the chi gung moves, my katas at a super slow motion, or while meditating. For all I know it is just blood moving through me. I don't think that is what it is, but I don't tend to describe it very well, because basically a lot of people would laugh at your attempts to wax mystical. Just, I do know what Hazrat means about it seeming to move better when you are in the bare feet. On the other hand if being barefoot makes it hard to concentrate on learning tai chi then there is no point in doing it that way. The movements themselves (and I don't know because I am not a sifu, expert, or anyone other than a very interested observer since my lessons stopped) presumably help to generate chi. I feel it in my hands first anyway, regardless of whether or not I am wearing shoes. This may just be the capilliaries opening as I relax - again, I haven't a clue.
This whole thread has made me really miss my classes! When are you doing your teaching tour Steve? Pretty please?