[c0l0]

Unless your users are of the kind who re-distribute your work (or something containing/extending your work - mostly aka software developers) all the time, switching from MIT to GPL is going to be just about no hassle at all to them.

[ssddanbrown]

Yeah, it wouldn't affect most users, but some users will be in that group. Plus it may (stupidly) raise legal term alerts for a portion of users it won't affect. As I said, is an option but one with concerns/considerations as per my last comment.