This isn't a bug, but the offer of a new feature. The timestamping feature doesn't quite work for us, as we don't keep just the latest view of a website and we don't want to copy all those files around for each update.
So I implemented a --changed-since=YYYYmmdd[hhmm] flag to only get files that have changed since then according to the header. It seems to work okay, although your extra check for file-size eqality for the timestamping feature makes me wonder if the date isn't always a good measure. One oddity is that if you point wget at a file that's older than the date at the top level, it won't be gotten and there won't be any urls to recurse on. (We're pointing it at an url that changes daily.) I tested it under Solaris 7, but there is a dependency on time() and gmtime() that I haven't conditionalized for autoconf, as I am not familiar with that tool. I would like this feature to get carried along with the rest of the codebase; would you like it? -dca