I'm sorry Mikf, but i'm still a bit confused.
These downloaded RGT files seem to me, to do exactly the same as my Style files, in that the file sets up the the whole piano, to suit a particular song. (these files are listed by song name)
Are you saying it will only do that, if that particular Style is aready loaded to my 805?
Yes, but more than that. It’s not enough to have the style, the registration needs to know where it is to locate it. So the registration may need re done. And as Toril says, if you really want to take it to the next level, even then it is not quite the same because the style itself may use different voices if taken from another keyboard model.
There are multiple ways to set up the keyboard for a specific song. Obviously you can do it manually every time, but the registration is a method that allows many keyboard parameters to be set, stored and re called instantly. These parameters are not just the style and the tempo, but the voices, Effects, pedal settings and many other settings.
You can also customize and store a style on the keyboard, and attach voices using the OTS system, and this may be adequate, but it doesn’t allow all the other parameters to be stored like a registration. Of course you may not need all these so it works well in that situation.
But because the registration is really just a set of pointers it is quite specific to your keyboard. So strictly speaking registrations would only be transferable between keyboards if they use preset styles, and are exactly the same model. They may sometimes appear to work when moved to other compatible keyboard models because the keyboard is quite smart about trying to find an alternative style that does exist on that keyboard. That may or may not be ok, but strictly speaking moving registrations between keyboards may take just as much effort to modify as to set it up on your keyboard in the first place.
Re legacy voices, - yes they are voices from older models. Yamaha has always done this on new models presumably because it’s easy and costs nothing, and some people may like the old voice. So you could say they are old technology, but they are playing through whatever sound system improvements are included in the new model, so maybe not completely ‘old’.
Mike