I believe that the Registry key which affects this is "AlwaysLaunchTemplate"
Now, here's where it gets really weird.
The value there is set to "0" (off) [just as it is in Sonar under Preferences]
If I change it in Sonar or in the Registry, it doesn't "take" - something on the Sonar start re-sets it back to "0" BUT, Sonar still loads the template.
In other words, I change the entry in both Preferences and the registry, but no - it doesn't take, and it doesn't work.
Bug report . . .