Frankly, webmin has always made me a bit nervous from a security standpoint and since I can do everything it does much quicker from command line I have never even considered installing it.

Who needs a gui when you can just perl -MCPAN -i 'install my::favorite::module' and go get some coffee? ;-)

But, it sounds like it fits your needs quite well so as with most things computer related I say, "whatever tool you find best"...I would only suggest you make webmin use SSL to strengthen it just a tad