Don’t know if anyone else here is a Reason fan, but this is a MAJOR step forward for the software after Propellerheads attempted to dominate third-party extensions in Reason with their own “rack extensions” plugin format.
I haven’t tried running any JUCE-derived code in Reason yet, but I’m sure it will work fine (Propellerhead’s stuff tends to be extremely high quality from my experience and probably conforms well to the VST standard). ROLI definitely needs to add host detection though!