With all respect, doesn't this sound somewhat hypothetical? I mean, how many clients like this have you had?
Also, the whole mirror thing I think was hot years ago, when business were connected to the Internet via slow lines. But now, with 10+ mbit connections available even for home use, does it really matter that much if the defs (which are typically < 200KB a day) were pulled directly from the Internet by each of the clients?
For a 100 client network, that's 20MB a day... does anyone care these days?
Thanks
Vlk