Unless you can find an unregistered CWPA 9, the short answer is no.
I started with CW Professional 6 and ended up staying with CWPA 9 for a while. Till Sonar 5 came out. And I thought CWPA 9 was a damn good program.
But now I am on Sonar Platinum, and I ain't even thinking about going back! I can do so much more, easier with what I have now.
This is a change if your use to CWPA 9, but I would suggest to stick with SPlat. If you need any help, there is lots of help on the Sonar forum. Just ask away!