Yes, we saw that in the release notes prior to upgrading, but had no clue the magnitude of changes necessary on our part if we were to implement the upgrade. Unless it is specifically noted, we expect core functionality to remain the same.
Based on the forum post
that I submitted regarding this issue, I understand the reason the change was necessary in order to accomplish the task you were trying to accomplish and I understand how to work around the change. But the honest truth is that after upgrading to the Q2 release our entire site needed to be retested because almost 95% of the RadComboBoxes no longer functioned as they did before, and validators no longer caught when an item was not selected. It's kind of a big deal when that much breaks. :-)
But back on topic, it seems that Andy is possibly also experiencing a side-effect of the change. I was just informing him of that core change so that he could more easily track down the problem within his code and do what is necessary in order to fix it.