Hi Crispin,
I've fixed the Bing Map to use the location alias for the text, so this will work in the next release of Event Calendar Pro. It shows a balloon on mouse over, the Show Location Balloon setting is really a google map specific thing.
As far as the point drifting, I agree it does seem to get less accurate as you zoom out, the behavior is the same in the Bing Msap feature as when using Bing Map in Event Calendar Pro. I found this thread where someone else was reporting the problem but the suggested solutions did not work for me. I tried using a custom icon and specifying the ImageOffset and while it did use the custom icon, nothing I tried seemed to affect the position of the icon.
The Bing Map embed code is an entirely different animal that uses an iframe, we are using the Bing Maps Ajax control.
There is a newer version but it looks like it is completely re-written and not backward compatible. I'll log an item in our project tracker and maybe at some point we can re-implement Bing Maps with the new version.
Best,
Joe