As some have said, I don't much care whether the new icon or the old icon is used. It is, after all, just an icon. However, I've noticed that the new icon (actually, the new icons for ALL the new beta versions) do not have any indication that the app is the Beta! On the old icons, the orange Beta symbol was visible and was a good indicator.
This is an issue because I always keep the MAS version of the programs and the BETA version of the programs on my Dock, using them both. As it stands now, there doesn't seem to be any way that we will be able to tell the difference.