I don't think there's really a huge difference in the comparable sizes... the difference seems to mainly be one of color choice and the fact that the women's line is available in smaller sizes

I am able to wear socks under my classics with no problem.... I would actually caution going up a size since they likely won't fit right with or without socks. These shoes already have enough 'give' for Injiji's or any thinner toe sicks (mine were some $3 big box find).. the entire upper material is stretchy.

My KSO's are really difficult to get on without socks... there's NO way I could wear them with any socks.

I don't think wide feet tend to be a problem with any of the vibrams because of the materials used.. the loudest complaining I have heard is from people with super narrow feet.