Guide to paniculata's ID...
...or from Russia with love :-)
These two great pictures were found on Russian forum (Websad.ru) and I think they could be of help:
Please note that some cultivars from the second picture are not available in US, but...maybe some day :-)
I'm for one would be interested to try a 'Great Star' because consensus of the discussion was that it's greatly varies depending on a growing conditions and age.
Here is a link that might be useful: