I've now finished the development of debiansynch and are looking for anyone, who likes to help in testing this script. I'm using the script now for almost a year, but have extented it lately with options I don't regularly use (particularly -A). The script and more info can be found at "http://dpartialmirror.sourceforge.net/".
So if anyone is interested in such a script and has the resources I'd appreciate any help. But be warned the script is still in beta. O. Wyss -- Author of "Debian partial mirror synch script" ("http://dpartialmirror.sourceforge.net/")