Recently I upgraded the RadControls to the latest version - Q2 and did not found issues. Please note that we have not tested the entire product and there might be some issues. I remember that I did this in the past and I had some problems with controls like Polls.
the Telerik team
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items