It seems to me, so far, that the only way to test new plug-ins is to allow VS3 migration and pay for membership, which automatically reassigns Sonitus inserts when you open projects and if you want to save projects makes that reassignment irriversible- Unless you 'Save as' and spend time opening projects manually, with or without VST3 migration. Always the risk of of sudden crashes or forgetfulness erasing your settings.
It's a case of 'Eithier Sonitus' or '(Untested & paid for) Core'. I can't open CbB now, but did find that my Sonar X2 doesn't accept the newer Cakewalk plug-ins, let alone the newest Sonar Core ones, so older projects seem to be fully intact- I can painstakingly collect the original Sonitus settings and reappropriate them so that Sonitus and Core plug-ins are both available in one project.
Still getting a lot of crashes on Sonar now, so I'm not sure if I'll be diving down the membership path yet- Even though the crash-dump appears to work far better than CbB ever did, which, in my experience, it rarely did.