Except that the calendar program won't work. I don't mean "will work in local mode but will not sync". I mean "will completely block you out from doing anything". Which means that if you get a tablet for a kid, for example, and don't want to link it to google but want to show them the habit of setting deadlines for their homework assignments, then you can't. This is on ICS.
Sure, when the disk image is served from the host system's buffer cache, why wouldn't it run quickly? Also, what display driver are you using there? Probably not one that requires tens of megs of RAM that are taken away from starved applications.