Yes. But it does read the Model Name description because it will show nuvi1300 (Unit ID xxxxxxxxxx). i.e.:
Now edit the GarminDevice.xml Model Description to 1350, and voila:
That doesn't mean it takes it into account any further of course, and as you said it's only the HWID which identifies the unit and determines the appropriate FW, and the current version which then determines if an update is needed [which is what i also said].
PS: I had 'WebUpdater reads only the Model-Description, ... etc', i meant 'WebUpdater only reads the Model-Description, ...'. Sorry.