For those asking men/womens sizes - many people on barefoot forums (mostly men) wear both mens and women's - the feeling is that is how you get 1/2 sizes - so if men can wear women's then women can wear men's LOL.
I have 2 pair of men's treks (size 40) and one pair of women's KSO (size 43) and they fit me identically.
Also my big toe definitely rams into the end of the shoe, it isn't a problem, you get used to it and IMHO tight is better, it allows your foot to work more.
I got the women's KSO trying to give my big toe more room, it didn't work that way, but it doesn't matter.
I also got my first pair in October, so I've been wearing socks. It'll be interesting when it warms up to see how the lack of socks affects the fit/comfort.