Prefetching really shouldn't be blindly applied to everything as users may have bandwidth limited. Even though your implementation is better than browser prefetch on users it does take the choice away from the user unless individual sites make it easy for users to opt out.
I think that if you stop hovering fast enough and the request is cancelled, you’ll end up only sending headers, thus not affecting bandwidth that much. Not sure though.
If not the case, note that it’s just HTML we’re wasting. In the grand scheme of things it seems to me it would not have that much of an impact on bandwidth usage.
