a higher proportion of IE-users amongst visitors from home than visitors from work
I don't think you can make this generalization. If you want to install a new browser on your home computer, you can do so at any time. Most people do not have such privileges at work. Corporate IT departments moreover are usually hesitant to adopt new software; some will deliberately wait for even a 1.1 version and while one might argue an alternative web browser would not interfere with other software, they in turn would argue that IE is "good enough for now" in most industries, so better to be cautious.