I'd worry about this for these reasons:

• Towards the future: when Microsoft decides it's time to update your browser, will it continue to work? Of course this applies to new versions of WWW::Mechanize as well, but at least that has a test-suite.
• MSIE is notorious for its security flaws. I would be hesitant about running this on a server platform.
• Who knows what information about the system MSIE sends to Microsoft. And what it can send "on demand".

Liz