Sorry for being late to this party but I have more to add on the subject:
I am of the opinion that a Scene is not an device but a trigger such that is has no 'status' but can be 'switched' in ISY terms.
Regardless of the particular levels each responder in a scene is programmed to respond at, if any controller of a given scene issues an ON, OFF, DIM or BRIGHTEN broadcast as a result of a physical press of the device then this should be able to be used as a trigger of an ISY program defined as:
If Control 'myScene' is switched On/Off/Dim/Brighten
If Status 'myScene' is [anything] would be invalid since a scene has no Status.
Since the PLM is a controller and responder of all scenes setup by the ISY, the PLM and hence the ISY would see all 'all link broadcast' messages from all scene controllers and would also receive the cleanup messages sent to each responder from the controller so it should just be a case of how the ISY chooses to interpret this.
Regarding a scene 'set' AKA triggered via REST or via an ISY program, then I think it may be breaking some 'rules' to have that count as a 'Control 'myScene...' event since it was not initiated by a physical action, however I could argue that an exception should be made for this particular case.
Also, for clarity, I would still expect the ISY to raise a Control and Status event for the individual device that was pressed, but if that device is also a controller of a scene then I think a 'control' event for the scene 'item' should also be raised as detailed above.
Anyway, I realise any of this would be new functionality for the ISY firmawre, but if the first step is to reach a proposal that work in all cases and is as intuitive as possible I would like to open this idea up to comment.
Thanks!