Actually this problem required a great deal of time. We spent a couple of days researching and trying to find the best solution, and it seems that instead of using an image that is flipped to show the reflection, it would be better to use the Effect feature of the Silverlight 3 to introduce a shader effect. The effect will represent a reflection and will get rid of the issue we face now with updating the reflection at the proper time. Stay tuned for our official release as we will do our best to release another great version of this control.
the Telerik team