To the OP: Assuming your hardware can support X2 and you can afford the cost of the upgrade I can't see any reason not to upgrade. You don't need to uninstall any previous versions so if your learning curve would impact your productivity you can maintain what you are currently using.
As for the 'history of unstable releases' you may want to consider that the majority of people who use Sonar do not comment on how well it is working. In the IT support biz we have a saying: "How come you never call me when it works?"
FWIW: I did the upgrade the day it was available and I have found it to be stable and the enhancements are really fantastic. I'd say go for it.
Regards