Glad you like the control. The problem with IE is that it doesn't like
it when you change the contents of DOM elements before the page is done
loading. Now people hate IE because it complies with the standards :-)

There are some workarounds.
The most popular is to run the map rendering code from the page body's
load event. This is somewhat bothersome when working with masterpages.
Another way is making a script block that uses the defer attribute, but
this is not guaranteed to work cross-browser.
Finally you can delay running the script manually by using a timeout,
but this sometimes causes trouble with very busy pages.

As you can see there is not a golden solution when working with master
pages as you don't have the possibility to write in the master file's
markup. So you have to do it programatically or use options 2 or 3.